Boss Monsters

 are NPCs found rarely in Terraria that are much harder to kill than other monsters. Any boss monster generally has much stronger attacks than a normal enemy, more defense, and considerably higher HP. In addition, most boss monsters have their own AI, allowing them set movements to go by. Since update 1.2, all bosses can drop a unique trophy (~10% drop rate) that can be placed on a wall for display.

Many bosses can be summoned by an item such as a Suspicious Looking Eye or Worm Food.

Pre-Hardmode

 * -|Eye of Cthulhu=

The Eye of Cthulhu (commonly referred to as The Eye) is usually the first boss players will encounter, this is due to the fact that The Eye is considered the easiest pre-hardmode boss. The Eye comes in two forms. The first form has 15 attack, while the second form has 23 attack. The Eye of Cthulhu can be summoned by using a Suspicious Looking Eye (which can either be found in random chests or can be crafted from 6 Lenses at a Demon Altar) at night. The Eye can also spawn itself if certain criteria are met. While playing, the player may get the message "You feel an evil presence watching you...", which means that the Eye will awaken soon. After a few minutes the message "The Eye of Cthulhu has awoken!" will appear and the boss will promptly start to attack the player. You can summon The Eye anywhere, as long as it is night. Sometimes when you are underground and you see "You feel an evil presence watching you...", and you die it will spawn after you respawn so you get killed twice in the period of 5 minutes.


 * -|Eater of Worlds=

The Eater of Worlds is a worm-type boss monster. It can be summoned in the Corruption by smashing three shadow orbs or by using Worm Food, which can be crafted at a Demon Altar - however, it can only be summoned in The Corruption.

The Eater of Worlds has 53 parts in three segments; head, body and tail. To beat this boss all segments must be slain. If the head is destroyed, the next body segment will automatically take its place as a head. The same happens with the tail. If you destroy a body segment, he will split into two separate worms. Overall, if you avoid the head's massive attack of 40, the boss is fairly easy to defeat, especially with weapons that deal damage multiple times per strike, such as Vilethorn.

It is the only boss that can drop Shadow Scales, which are needed to forge Shadow Armor.


 * -|Brain of Cthulhu=

Brain of Cthulhu is a new boss introduced in Terraria v1.2, being the alternative to Eater of Worlds if your world has Crimson. Brain of Cthulhu can be summoned using an item called "Bloody Spine". Otherwise, you can also summon the boss by breaking orbs similar to Eater of Worlds. Instead of having segments like the Eater of Worlds, it has minions called Creepers that orbit it and fly off occasionally to attack you. It teleports all this time, and it is invincible until all Creepers are killed. Then it morphs into its 2nd form and has 1000 health, and tries to attack you itself. It is the only boss to drop Tissue Samples, which is the Crimson version of Shadow Scales used to craft many Crimson materials.


 * -|Queen Bee=

The Queen Bee is a boss that is summoned by breaking a larva type object found in a hive which spawns in the Underground jungle. Once spawned the Queen will begin to alternate between diving attacks from either side of the screen, and hovering above you, either shooting stingers or spawning tiny bees.


 * -|Skeletron=

Skeletron is a boss which can be defeated as many times per world as wanted using the Clothier Voodoo Doll. The first way to summon him is to talk to the Old Man in front of the dungeon at night and choosing the option "Curse". It is advised to be prepared because after that he will transform into Skeletron and attack you. His hands each have and his head has. His hands do 30 damage if they touch you and his head will do a spin attack that does 35 damage. Be quick to defeat this boss and summon him at the very beginning of night because once dawn comes Skeletron will hit you for 9999 damage, resulting in instant death. If you die before defeating Skeletron, you will not be able to fight him again until the next night, when the Old Man will respawn.

After defeating Skeletron, the player will gain access to the Dungeon.

The Wall of Flesh (commonly abbreviated as WoF) is an aptly named wall made out of flesh that is the height of the entire Underworld Biome. It is the main boss of the Underworld, and defeating it in a world will permanently activate Hard Mode for that world. It is summoned only when the Guide is killed by allowing a Guide Voodoo Doll to fall into lava in the Underworld (Make sure the guide is alive when you drop the voodoo doll in, or it won't spawn the WoF). The Wall of Flesh moves constantly in the same direction, forcing the player into an on-the-run battle.
 * -|Wall of Flesh= WoF Complete.png

Hardmode

 * -|The Twins=

The Twins are the hardmode counterpart to the Eye of Cthulhu, except there's two of them, and they are both connected together as seen in the photo. The Twins, namely Retinazer and Spazmatism, are bosses summoned with the item Mechanical Eye.

They have similar attack patterns to The Eye of Cthulhu, but their second forms use laser and demon fire attacks respectively. The two both need to be defeated to count as a boss kill. The Twins will spawn randomly in hardmode until they are defeated.


 * -|The Destroyer=

The Destroyer is a worm type boss monster. It is the Hardmode counterpart of the Eater of Worlds. However, unlike the Eater of Worlds, it does not split into parts. The Destroyer is summoned with the item Mechanical Worm. The Destroyer will spawn randomly in hardmode until it is defeated.

The Destroyer drops 15-30 Souls of Might and 5-15 Greater Healing Potions. Souls of Might are required to make many Hardmode weapons and tools, like the Excalibur and Megashark. Getting the souls can sometimes be a problem, as if the Destroyer is defeated while mostly underground the Souls of Might may be dropped on top of blocks.


 * -|Skeletron Prime=

Skeletron Prime is the Hardmode counterpart of Skeletron. Similar to The Destroyer, he is also made of metal. Skeletron Prime is summoned with the item Mechanical Skull. Skeletron Prime will spawn randomly in hardmode until it is defeated.

Skeletron Prime drops 20-30 Souls of Fright and 5-15 Greater Healing Potions. Souls of Fright are required to make many Hardmode weapons and tools.


 * -|Plantera=

Plantera is a hardmode boss with no pre-hardmode counterpart. To summon Plantera, player must fulfill a criterion: before meeting Plantera, the player has to defeat at least one mechanical (Twins, Destroyer, or Skeletron Prime) hardmode boss. After the player has met the criteria, you need to locate a pink plant which is relatively common in the Jungle. Plantera has two forms: the first form looks similar to the pink plant, with high defense. Its second form, is the pink canopy is tore off, and Plantera formely looks like a Man Eater; in this form, Plantera will speed up and lose defense but raise its attack sharply. Plantera will always drop Temple Key and have a chance to drop: Grenade Launcher, Venus Magnum, Pygmy Staff, Nettle Burst, Wasp Gun, Flower Pow, Leaf Blower and Seedling.


 * -|Golem=

Golem is technically not a hardmode boss, but he has the power and requirements of one. It is summoned by taking Lihzahrd Power Cells to the altar found in the Jungle Temple, opened with a key from beating Plantera. On the first stage he will launch various attacks at you such as extending his fists, launching fireballs and lasers. In the second stage his head detaches and you have to hit the body. Golem drops one of the following: Sun Stone, Stynger, Possessed Hatchet, Eye of The Golem, Picksaw, Heat Ray, Staff Of Earth, or Golem Fist.

Event Bosses

 * -|Pumpking=

The Pumpking is a Hardmode boss that spawns during the Pumpkin Moon. It behaves very similarly to Skeletron. It has two lengthy arms, each with a large scythe. These hands act much like Skeletron's hands, but they are indestructible.

It is considered the final boss of the Pumpkin Moon, and subsequent waves after its appearance increase the number of mobs. There can be a large number of Pumpkings attacking at once in the later stages (up to 6 active at the same time).


 * -|Santa-NK1=


 * -|Ice Queen=


 * More info Desired

The Ice queen is the Final Boss of The Frost Moon Event. The Ice Queen attacks with three phases. It could either swoop down quickly to touch the player, causing high damage to the player in a short time. Second, it could spin around while quickly spawning frost shards that go in random directions. These frost shards do decent damage, but if many of them hit the player, it could kill the player quickly. Another phase is that it could shoot frost waves that have high velocity and can go through blocks. It does quite high damage and is fired at a fast rate towards the player, so players might find this phase difficult. Once killed she has a 16.6% chance to drop one of the following: Snowman Cannon, North Pole, Blizzard Staff, Baby Grinch Mischief's Whistle, or Reindeer Bells.

Mini-bosses

 * -|King Slime=

The King Slime, as one might gather, is a slime. It is blue in color and enormous, roughly 10 blocks wide and 5 blocks high. It will decrease in size and spawn blue slimes when it takes damage. It appears to have a Ninja trapped inside it.

King Slime is summoned with the item Slime Crown, crafted with a Gold Crown and 99 gel at a Demon Altar. There has been a bug associated with the King Slime, sometimes causing the boss to not spawn/appear. This may be due to the fact that he spawned inside a cave and cannot get out.

The King Slime actually drops a little amount of Gel when he dies, and all of the blue slimes spawned when the King Slime is attacked also drop gel. The King Slime also drops gold coins, a piece of the Ninja Set and some lesser healing potions.

The King Slime is the biggest slime in the game so far.


 * -|Ice Golem=

Ice Golems are an Uncommon miniboss. They spawn in Snow Biomes after activating Hard Mode, during a Blizzard. They will spawn more often during a Blood Moon. Ice Golems are hostile and thus attack the player. While they are able to deal damage by physical contact, they are very slow and will shoot at the player with lasers from afar, which also have a chance to cause a debuff. They are affected very little by knockback, but have a low jump height of only about 3 blocks.


 * -|Wyvern=

The Wyvern is a large Hard Mode Mini-Boss. It is a curling, dragon-like creature that attacks at high speed.

Wyvern is not summoned - it occasionally spawns in the sky, around the same point that Harpies spawn. It spawns without warning, so the player should be careful when they are at a high elevation in hardmode.


 * -|Paladin=

The Paladin spawns rarely in Hard Mode Dungeons. It throws hammers that will go through walls at the player and will try to walk into the player. When taking constant damage it will stop throwing hammers, but will still walk towards the player, as it is unaffected by knockback.


 * -|Mourning Wood=

Mourning Wood are monsters that spawn during the Pumpkin Moon event. They shoot flaming projectiles that deal considerable damage to the player. Mourning Wood have 3 different kind of attacks: shooting fire projectiles that pierce through solid objects, spraying a cluster of lingering flames onto the ground, and hurting the player by touch.

The best strategy for taking out Mourning Wood is to used ranged attacks, as their piercing shots come at random intervals and are difficult to dodge. Ranged, Magic, or high knockback weapons are recommended.


 * -|Everscream=

Everscream is a miniboss in the Frost Moon event, and is comparable to the Mourning Wood. It is a pine tree with red glowing eyes and is covered with snow. Everscreams appear in the fifth wave and onward of the event.

Console Version
The Ocram's attack style is very similar to that of the Eye of Cthulhu. Like the Eye of Cthulhu, it charges repeatedly at the player while summoning servants. Additionally, it fires numerous red laser beams. The Ocram has in total 35,000 HP and after knocking its health down to halfway, it will (like most bosses) switch into its second mode, where it continues to summon servants, but will charge constantly and the laser changes to a blue, more damaging laser. Ocram also uses the demon scythe spell summoning several demon scythes at once doing a fair amount of damage. Souls of Blight are Souls dropped by Ocram. It would take 255 Souls to make all the relevant items. That means you need to Defeat Ocram 17 to 51 times in order to craft all of the relevant items using the Souls of Blight. The Arch Wyvern is a type of Wyvern found in console Hardmode. With double the health of a normal Wyvern and a damage output of 70-90 damage, the Arch Wyvern is a fearsome foe. It can go through blocks, but if you walk too far away from it, the Arch Wyvern will despawn. Even though it has twice as much health as the regular wyvern it still has the same amount of drops. Be careful not to fight this too close to your main house as it can follow you back home and kill your NPCs.
 * -|Ocram=
 * -|Arch Wyvern=

Trivia

 * There is an upcoming boss currently known simply as the Lunar Boss. Nothing is known about this boss as of now, but the boss theme has been released with the Terraria Soundtrack Vol. 2.