Bosses

Bosses are large, aggressive, resilient enemies that offer a substantial challenge to players. Defeating bosses is usually instrumental in advancing the game in some way. Each has its own particular way of being summoned, and warning messages appear whenever one is about to appear. When the boss appears, its own special boss music will play, indicating that the fight has begun, along with a message saying it has arrived. Defeating a boss concludes with a congratulatory message and several items. Most of the bosses can pass through blocks of all types, with the exception of King Slime, Lepus, Turkor the Ungrateful's body , the Flying Dutchman, and Golem.

On the, bosses will appear on the minimap, and are the only enemies to do so. This allows the player to locate them easier.

Most bosses have items associated with them which summon them when used, usually directly. However, some must be used with the help of another block to complete the summoning. Bosses that are summoned directly from items have other ways to be summoned, most commonly either appearing during nightfall or able to be summoned by breaking Shadow Orbs or Crimson Hearts. Event-exclusive bosses only appear during their respective events.

Pre-Hardmode Bosses
These are the first bosses the player can encounter. Usually, defeating one of these bosses will give the player items and materials necessary to progress in the game, eventually leading to Hardmode.

Hardmode Bosses
Hardmode Bosses are significantly harder upgrades of and new additions to previous bosses. Defeating them is usually instrumental in advancing the game in some way. Each has its own particular way of being summoned, and warning messages appear whenever one is about to appear. Defeating a boss concludes with a congratulatory message and several items.

During Hardmode, each night has a one in two chance of spawning one of the three Mechanical Bosses that have not yet been defeated in the current world. This only happens after removing at least one Altar from the world, so it may be advisable to refrain from doing so if the player is not ready for a challenging fight.

Achievement
Slayer of Worlds is the achievement you earn for defeating all of the bosses (excluding those exclusive to Events) in the game ( only). Exterminator is the achievement you earn for defeating every boss in the game ( only).

History
Boss Боссы