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NPCs in this wiki generally refer to town NPCs, however for the purpose of this article they also include Enemies and Critters

AI (or artificial intelligence) is the behavioral pattern exhibited by an NPC. For instance, the Caster AI will always warp, shoot three times, pause for three seconds, and then warp again. Knowing the AI an enemy uses can provide an advantage in combat, as it offers an idea of how the enemy will attack and react in given scenarios.

In addition, additional AI is added for certain NPCs, such as the non-aggressive mode of surface Slimes, the Eater of Souls' circling around the player, the Wandering Eye's acceleration, and the ranged attack of some Fighter AI enemies.

AIs are not given names in the game code, so they are given names here to assist in identifying them across the wiki. Most AI names are given based on observed behavior (such as Flying AI), NPC groups (such as Slime AI), or the first NPC to implement the AI (Such as Demon Eye AI).

There are 112 different AI types:

ID Name Description NPCs
0 No AI Doesn't move. Bound Goblin, Bound Wizard, Bound Mechanic, Webbed Stylist, Sleeping Angler, Turkor the Ungrateful's Body3DS Version, Unconscious ManDesktop Version
1 Slime AI Hops in one direction, slides on slopes, floats in water, follows player if damaged or it's nighttime. All Slimes (except King Slime), Hoppin' Jack, Grasshopper
2 Demon Eye AI Flies, follows player, bounces off walls in an arc. Demon Eye, Wandering Eye, The Hungry II (part of Wall of Flesh), Pigron
3 Fighter AI Will walk, jump over holes, follow player. It will try to line up vertically first. If it fails to reach its target, it will back up a bit, then re-attempt. It is the most common AI in Terraria. Zombie, Skeleton, Undead Miner, Skeleton Archer, Angry Bones, Armored Skeleton, Goblin Scout, Goblin Archer, Goblin SummonerDesktop VersionConsole VersionMobile Version, Corrupt Bunny, Crab, Antlion Charger, Werewolf, Clown, Chaos Elemental, Possessed Armor, Mummy, Spectral ElementalOld-gen console version3DS Version, Vampire (humanoid form), The PossessedDesktop VersionConsole VersionMobile Version (climbs walls), Vampire Miner, Frankenstein, Swamp Thing, Undead Viking, Corrupt Penguin, Face Monster, Snow Flinx, Nymph, Armored Viking, Lihzahrd, Icy Merman, Pirate Deckhand, Pirate Corsair, Pirate Deadeye, Pirate Crossbower, Pirate Captain, Cochineal Beetle, Cyan Beetle, Lac Beetle, Sea Snail, Ice Golem, Eyezor, Anomura Fungus, Mushi Ladybug, Rusty Armored Bones, Blue Armored Bones, Hell Armored Bones, Bone Lee, Paladin, Skeleton Sniper, Tactical Skeleton, Skeleton Commando, Scarecrow, Splinterling, Zombie Elf, Elf Archer, Gingerbread Man, Nutcracker, Yeti, Krampus
4 Eye of Cthulhu AI Alternates between trying to stay above the player and summoning Servants of Cthulhu, and charging at the player occasionally. Spins when at low health, and begins exclusively charging at the player. Always looks at player. Eye of Cthulhu
5 Flying AI Flies, looks at player, follows player. Servant of Cthulhu, Eater of Souls, Corruptor, Hornet, Probe, Crimera, Moss Hornet, Moth, Bee, Parrot, Dragon HornetOld-gen console version3DS Version, Servant of OcramOld-gen console version3DS Version, Meteor Head
6 Worm AI Burrows in ground (and/or air), passes through blocks, follows player. All parts of the following: Giant Worm, Devourer, Bone Serpent, Eater of Worlds, Digger, World Feeder, Wyvern, Arch WyvernOld-gen console version3DS Version, Leech, Crawltipede, Mythical Wyvern
7 Passive AI Walks semi-randomly, jumps over holes.

As of the 1.3 update, all Passive NPCs talk to each other and the player, and each NPC has a different weapon to defend themselves when an enemy is nearby.

All Town NPCs, Traveling Merchant, Old Man, Bunny, Penguin, Squirrel, Mouse, Frog, Scorpion, Black Scorpion
8 Caster AI Casts spells at player, stays stationary, warps after three casts, warps if falling. It stops casting spells if damaged, then warps if left alone. Fire Imp, Goblin Sorcerer, Dark Caster, Necromancer, Diabolist, Ragged Caster, Tim, Rune Wizard
9 Spell AI Travels in a direct line toward player, going through blocks. Used by casters. Burning Sphere, Chaos Ball, Vile Spit, Water Sphere
10 Cursed Skull AI Tries to drift toward or around player, often stays a little bit out of reach once having touched the player. Cursed Skull, Giant Cursed Skull, Dragon SkullOld-gen console version3DS Version
11 Head AI Tries to stay above player, spins and moves towards player occasionally. Skeletron Head, Dungeon Guardian (Indefinitely moves towards player)
12 Skeletron Hand AI Waves, damages player. Skeletron Hand
13 Plant AI Extends on a vine towards player, looks at player. Dies if not rooted to a block. Snatcher, Man Eater, Clinger, Dragon SnatcherOld-gen console version3DS Version, Angry Trapper, Fungi Bulb, Giant Fungi Bulb
14 Bat AI Spasmodically flies toward player. Harpy, Cave Bat, Jungle Bat, Ice Bat, Lava Bat, Giant Flying Fox, Hellbat, Demon, Voodoo Demon, Giant Bat, Illuminant Bat, Slimer, Arch DemonOld-gen console version3DS Version, Red Devil, Vampire (bat form), Flying Snake
15 King Slime AI Hops toward the player, releases Blue Slimes when damaged (releases Spiked Slimes when damaged in Expert mode), teleports toward the player when player is out of reach. King Slime
16 Swimming AI Swims back and forth, moves towards the player if they are in water. Corrupt Goldfish, Piranha, Arapaima, Shark, Blood Feeder, Angler Fish, Crimtane Goldfish OrcaOld-gen console version3DS Version
17 Vulture AI Stands still until player gets within five blocks of AI or is damaged. AI then acts similarly to the Flying AI. Vulture, Raven
18 Jellyfish AI Floats back and forth, swims toward player in small bursts if player is in water. Blue Jellyfish, Pink Jellyfish, Green Jellyfish, Squid, Blood Jelly, Fungo Fish
19 Antlion AI Looks at player, climbs overlapping blocks, shoots falling sand at nearby players. Antlion, Albino AntlionOld-gen console version3DS Version
20 Spike Ball AI Swings in a circle from a pivot point on a chain. Spike Ball
21 Blazing Wheel AI Moves along walls, floors and closed doors. Blazing Wheel
22 Hovering AI Similar to the Fighter AI, floats over the ground instead of jumping. Wraith, Pixie, Gastropod, Spectral GastropodOld-gen console version3DS Version, Ice Elemental, Floaty Gross, Reaper, Ichor Sticker, Ghost, Poltergeist
23 Flying Weapon AI Doesn't adhere to gravity or tile collisions. Spins several times, then heads straight towards the player. Any damage cancels its attack and forces it to spin again. Cursed Hammer, Enchanted Sword, Shadow HammerOld-gen console version3DS Version, Crimson Axe
24 Bird AI Stands still until player gets nearby, then flies away. Avoids walls and obstacles and changes direction if one is in the way. Bird, Cardinal, Blue Jay
25 Mimic AI Stands still until player approaches or attacks, then leaps towards them with varying heights. Mimic, Present Mimic
26 Unicorn AI Slowly gains speed while moving, jumps over obstacles. Unicorn, Wolf, Hellhound, Headless Horseman, Angry TumblerDesktop Version, TwinkleDesktop VersionConsole VersionMobile Version
27 Wall of Flesh AI Wall of Flesh Mouth with Wall image attached. Traverses the world horizontally. Also spawns with two Wall of Flesh Eyes which share its health. Wall of Flesh Mouth
28 Wall of Flesh Eye AI Bound to an entity, watches player, and shoots projectiles. The more damaged it is, the more it shoots. Wall of Flesh Eye (Bound to Wall of Flesh)
29 The Hungry AI Similar to the Plant AI, but attached to an entity. The Hungry (part of Wall of Flesh)
30 Retinazer AI Alternates between attempting to stay diagonally above player while shooting projectiles slowly, and attempting to stay beside player and shooting projectiles very rapidly. Retinazer
31 Spazmatism AI Alternates between shooting projectiles and staying beside player, and charging toward player. Spazmatism
32 Skeletron Prime Head AI Same as Head AI Skeletron Prime
33 Prime Saw AI Occasionally charges at the player, heads directly towards player when enraged. Prime Saw
34 Prime Vice AI Occasionally charges at the player, rapidly charges when enraged. Prime Vice
35 Prime Cannon AI Fires bombs upwards, aims directly at player when enraged. Prime Cannon
36 Prime Laser AI Fires projectiles at player, shoots very rapidly when enraged. Prime Laser
37 The Destroyer AI Similar to worm AI except it will shoot projectiles from the body and tail and is unable to "fly" in air. It will also release Probes. The Destroyer
38 Snowman AI Jumps and runs toward the player, similar to Fighter AI. Snowman Gangsta, Mister Stabby, Snow Balla
39 Tortoise AI Crawls a bit, then leaps toward player. Will indefinitely leap towards the player in water. Giant Tortoise, Ice Tortoise, Giant ShellyDesktop VersionConsole VersionMobile Version, SrollerDesktop VersionConsole VersionMobile Version
40 Spider AI Capable of climbing background walls as well as through platforms. Used only when crawling on a wall. Without a wall listed enemies seamlessly transform into their walking variants, which use Fighter AI. Black Recluse, Wall Creeper, Jungle Creeper, Blood Crawler, Sand Poacher, The Possessed
41 Herpling AI Jumps high and attempts to land on the player. It can strafe to the sides in midair. Herpling, Derpling
42 Lost Girl AI Turns into a Nymph when a player gets too close. Lost Girl
43 Queen Bee AI Alternates between attempting to stay above player while firing projectiles downwards or spawning bees, and charging back and forth very rapidly. Queen Bee
44 Flying Fish AI Flies straight towards player. Flying Fish, Antlion Swarmer
45 Golem Body AI Jumps towards player every few seconds, shoots lasers. Golem Body
46 Golem Head AI Bound to an entity. Golem (Bound to Golem Body)
47 Golem Fist AI Flies towards player, returns when hit. Golem Fist
48 Free Golem Head AI Attempts to fly back and forth, shoots projectiles at player. Golem Head
49 Angry Nimbus AI Attempts to stay directly above the player, and fires projectiles downwards. Angry Nimbus
50 Spore AI Drifts downwards while following player, destroyed on contact. Fungi Spore, Spore
51 Plantera AI Clings to nearby blocks, chases player, fires projectiles and spiky balls that bounce around. Plantera
52 Plantera's Hook AI Moves forward briefly before latching onto a block. Plantera's Hook
53 Plantera's Tentacle AI Acts very similar to the Plant AI, only bound to a certain entity. Plantera's Tentacle
54 Brain of Cthulhu AI Doesn't adhere to gravity or tile collisions, and teleports occasionally in first form. Once all Creepers are killed, it will begin rapidly teleporting and moving toward the player. Brain of Cthulhu
55 Creeper AI Circles around an entity, charging at player. Creeper (Circles Brain of Cthulhu)
56 Dungeon Spirit AI Moves directly towards player, gaining momentum. Emits blue-ish particles. Dungeon Spirit
57 Mourning Wood AI Moves towards player, stops, and fires projectiles straight at the player. Mourning Wood, Everscream
58 Pumpking AI Very similar to the Head AI. Spawns with two Pumpking Scythes. Pumpking
59 Pumpking Scythe AI Very similar to the Hand AI. Pumpking Scythe
60 Ice Queen AI Flies around, shooting a barrage of ice-based projectiles. Ice Queen
61 Santa-NK1 AI Moves across the ground, stops moving, and launches many different types of projectiles. Santa-NK1
62 Elf Copter AI Attempts to fly around the player, shooting bullets rapidly if they are in sight. Elf Copter
63 Flocko AI Flies towards the player at high speed. Flocko
64 Firefly AI Flies slowly in any direction and occasionally glows. Firefly, Lightning Bug
65 Butterfly AI Flies slowly in any direction. Butterfly
66 Passive Worm AI Moves along the ground, pause for a bit, then continue moving. Will avoid walls and moves in the other direction if it has hit one. Worm, Truffle Worm (Desktop VersionConsole VersionMobile Version Burrows in ground when a player gets close)
67 Snail AI Acts similarly to the Passive Worm AI, but climbs up walls instead of moving away. Snail, Glowing Snail
68 Duck AI Swims in water, or walks on land. Will fly away when a player is nearby, landing after a while. Duck, Mallard Duck
69 Duke Fishron AI Rams player multiple times before summoning entities. In second form, it flies in circles and summons entities. Duke Fishron
69 Lepus AI 3DS Version Jumps similarly to King Slime, generates entities while on the ground. Lepus (Generates Lepus Eggs)
70 Detonating Bubble AI Flies through the air, chases player, and disappears after a period of time. Detonating Bubble (Explodes and deals damage if it succeeds in reaching player)
71 Sharkron AI Follows an arcing path, dies when it touches a wall or player. Sharkron
72 Bubble Shield AI Desktop VersionConsole VersionMobile Version Created by the Martian Officer, absorbs all damage dealt to the officer. Bubble Shield
73 Tesla Turret AI Desktop VersionConsole VersionMobile Version Built by Martian Engineers on the ground. Tesla Turret
74 Corite AI Desktop VersionConsole VersionMobile Version Travels through blocks, charges at the player. Corite
75 Rider AI Desktop VersionConsole VersionMobile Version Has a Rider and a corresponding mount, if one is destroyed the other keeps attacking. Dutchman Cannon, Drakomire Rider, Scutlix Gunner, Martian Saucer Turret
76 Martian Saucer AI Desktop VersionConsole VersionMobile Version Flies around the player, fires a Death Ray straight down, can only be damaged if all four turrets have been destroyed. Martian Saucer
77 Moon Lord Core AI Desktop VersionConsole VersionMobile Version Positions behind the player, invulnerable until the Moon Lord's head and hands are defeated. Moon Lord Core
78 Moon Lord Hand AI Desktop VersionConsole VersionMobile Version Files to the left and right of the player, opens and closes, fires Phantasmal Spheres, Phantasmal Eyes, and Phantasmal Bolts. Spawns True Eye of Cthulhu when health is depleted. Moon Lord Hand
79 Moon Lord Head AI Desktop VersionConsole VersionMobile Version Flies above the player, shoots a Phantasmal Deathray and then some Phantasmal Bolts, spawns True Eye of Cthulhu when defeated. Moon Lord Head
80 Martian Probe AI Desktop VersionConsole VersionMobile Version Floats at a constant height, turns red and files away if the player gets near it, triggers the Martian Madness event if it gets off screen. Martian Probe
81 True Eye of Cthulhu AI Desktop VersionConsole VersionMobile Version Flies around the Moon Lord, shoots Phantasmal Sphere, Phantasmal Deathray, Phantasmal Eye and Phantasmal Bolts at the player. True Eye of Cthulhu
82 Moon Leech Clot AI Desktop VersionConsole VersionMobile Version Travels from the player to the Moon Lord's head, heals part of the Moon Lord for 1000 HP if it reaches the mouth. Moon Leech Clot
83 Lunatic Devote AI Desktop VersionConsole VersionMobile Version Never moves, causes the Lunatic Cultist to spawn when all are killed. Lunatic Devote
84 Lunatic Cultist AI Desktop VersionConsole VersionMobile Version Teleports around the player, fires shadow fireballs, ice mist, fireballs and lighting orbs. Creates duplicates of itself and summons Phantasm Dragons and Ancient Visions, triggers Lunar events when defeated. Lunatic Cultist
85 Star Cell/Brain Suckler AI Desktop VersionConsole VersionMobile Version Flies around the player, slowly floats towards them. Usually sticks to the player. Brain Suckler, Star Cell, Deadly Sphere
86 Ancient Vision AI Desktop VersionConsole VersionMobile Version Flies around the player, does not adhere to gravity or tile collisions. Ancient Vision, Shadowflame Apparation
87 Biome Mimic AI Desktop VersionConsole VersionMobile Version Passive until approached by the player. Attacks by jumping, dashing rapidly, and jumping into the air and slamming down on the player, ignoring block collision. Periodically "shuts" and becomes immune to damage and reflects projectiles in Expert Mode. Hallowed Mimic, Crimson Mimic, Corrupt Mimic
88 Mothron AI Desktop VersionConsole VersionMobile Version Flies through blocks, lunges at the player, occasionally lays a Mothron Egg. Mothron
89 Mothron Egg AI Desktop VersionConsole VersionMobile Version Doesn't move, spawns Baby Mothrons after a while. Mothron Egg
90 Baby Mothron AI Desktop VersionConsole VersionMobile Version Spawns from Mothron Eggs, flies, lunges at the player. Baby Mothron
91 Granite Elemental AI Desktop VersionConsole VersionMobile Version Floats towards the player, passing through tiles if the player is far enough. Drops to the ground when hurt in Expert mode. Granite Elemental
92 Target Dummy AI Desktop VersionConsole VersionMobile Version Stationary, recoils when damaged. Target Dummy
93 Flying Dutchman AI Desktop VersionConsole VersionMobile Version Floats about the player, is defeated when all 4 cannons are destroyed. Flying Dutchman
94 Celestial Tower AI Desktop VersionConsole VersionMobile Version Bobs up and down in place, can only be damaged when 100 / 150 of its event enemies are defeated. Triggers Moon Lord to spawn when all 4 are defeated. Solar Pillar, Vortex Pillar, Nebula Pillar, Stardust Pillar
95 Small Star Cell AI Desktop VersionConsole VersionMobile Version Remains stationary, eventually grows into a full sized star cell. Small Star Cell
96 Flow Invader AI Desktop VersionConsole VersionMobile Version Floats around the player, summons 3 orbiting minions, fires projectiles at the player. Flow Invader
97 Nebula Floater AI Desktop VersionConsole VersionMobile Version Floats around the player, summons 3 orbiting minions, charges at the player and fires laser while teleporting. Nebula Floater
98 Unknown
99 Solar Fragment AI Desktop VersionConsole VersionMobile Version Spawned from the "mouth" of the Solar Pillar. Shot upward on spawn and gradually falls down to the ground, destroyed on contact with blocks or the player. Solar Fragment
100 Ancient Light AI Desktop VersionConsole VersionMobile Version Fired in spreads of five by the Lunatic Cultist. Ancient Light
101 Ancient Doom AI Desktop VersionConsole VersionMobile Version Spawned from Lunatic Cultist in Expert mode, fires 4 projectiles in a "+" shape when defeated/summoned. Ancient Doom
102 Sand Elemental AI Desktop Version Floats around, moving towards the player, and occasionally spawns three 'sandnados'. Gets faster the more it is damaged. Sand Elemental
103 Sand Shark AI Desktop Version Hides under sand (and its variants), occasionally dashes at the player. Sand Shark, Bone Biter, Flesh Reaver, Crystal Thresher
104 Unknown Currently, no NPCs follow this AI. Its specifics are unknown.
105 Eternia Crystal AI Desktop Version Stays still, targeted by Old One's Army monsters, ends the Old One's Army event if health reaches 0. Eternia Crystal
106 Mysterious Portal AI Desktop Version Spawns Etherian enemies. Mysterious Portal
107 Attacker AI Desktop Version Moves towards the Eternia Crystal to attack it, and floats through blocks if it can't reach the crystal. Etherian Goblin, Etherian Goblin Bomber, Etherian Javelin Thrower, Ogre, Kobold, Wither Beast, Old One's Skeleton, Drakin
108 Flying Attacker AI Desktop Version Flies above the Eternia Crystal, pauses, and then dives for it. The cycle then repeats. Kobold Glider, Etherian Wyvern
109 Dark Mage AI Desktop Version Slowly moves towards the Eternia Crystal. Occasionally summons multiple Old One's Skeletons around it and heals enemies. Dark Mage
110 Betsy AI Desktop Version AI behaves similarly to the Duke Fishron AI. Shoots fireballs and rarely sweeps over the crystal with Flame Breath. Betsy
111 Etherian Lightning
Bug AI Desktop Version
AI behaves similarly to the Hovering AI. Shoots lightning below it repeatedly. Etherian Lightning Bug