Bosses are tough, usually massive creatures in Terraria that have tons of health, lots of defense, and deal massive amounts of damage. Most bosses must be summoned with a special item before they can be fought, though a couple spawn on their own. You will need two worlds for this, one with the Crimson ( Hallow ), and one with the Corruption.There are currently 13 bosses ( PS3/PS Vita )  18 bosses ( PS4 ) that count for this trophy, 7 (PS3/PS Vita)  10 ( PS4 ) of which are exclusive to Hardmode. On hardmode, the three noted Mechanical Bosses have a 10% chance of spawning each night naturally until they are defeated, at which point they will no longer spawn naturally.All bosses and their respected summon item (if applicable) are listed below. Mechanical Bosses are denoted with a **.
Each summon item is a link which will show you how to craft that item.

Name	Image	Summon Item or Requirement	PS3 /  PS VITA	PS4
King Slime		Slime Crown - Also has 1/300 chance to spawn in place of another Slime in the outer thirds of the map.	✅	✅
Eye of Cthulhu		Suspicious Looking Eye at night - Also has 1/3 chance to spawn each night when the player has 10+ Defense, 3 NPCs, and 10+ hearts until defeated.	✅	✅
Brain of Cthulhu		Bloody Spine in the Crimson - Also spawns every three broken Crimson Altars.	✅	✅
Eater of Worlds		Worm Food in the Corruption - also spawns every three broken Demon Altars.	✅	✅
Queen Bee		Abeemination in the Jungle, or destroy the Larva in the Hive in the Underground Jungle.	✅	✅
Skeletron		Speak to the Old Man at the Dungeon at night. Death allows the Clothier to spawn, thus needed for Real Estate Agent.	✅	✅
Wall of Flesh		Throw the Guide Voodoo Doll into the lava in the Underworld. Defeat activates Hardmode, thus needed for It's Hard!.	✅	✅
The Twins** - HARDMODE		Mechanical Eye at night - Also has a 10% chance to spawn per night until defeated.	✅	✅
Skeletron Prime** - HARDMODE		Mechanical Skull at night - Also has a 10% chance to spawn per night until defeated.	✅	✅
The Destroyer** - HARDMODE		Mechanical Worm at night - Also has a 10% chance to spawn per night until defeated.	✅	✅
Plantera - HARDMODE		No summon item; Defeat any Mechanical Boss, then find and destroy its bulbs in the Underground Jungle to make it spawn. Drops Temple Key on death which is needed to fight Golem.	✅	✅
Golem - HARDMODE		No summon item; Defeat Plantera, then use the key it drops to get into the Lihzahrd Temple in the Underground Jungle, and use a Lihzahrd Power Cell (found in the temple) on the Lihzahrd Altar (in the temple) to make it spawn.	✅	✅
Ocram - HARDMODE		Suspicious Looking Skull at night.	✅	⛔
Duke Fishron - HARDMODE		Summoned by fishing in the Ocean using a Truffle Worm as bait	⛔	✅
Empress of Light - HARDMODE		Summoning. The Empress of Light is summoned in the Hallow Biome by killing a Prismatic Lacewing, a rainbow butterfly that spawns in the surface Hallow at night between 7:30 PM - 12:00 AM. After killing the Empress of Light, Fae Flayer will unlock.	⛔	✅
Moon Lord - HARDMODE		Post-Lunatic Cultist boss. Spawned by destroying the four Celestial Pillars or by using a Celestial Sigil in any world where Golem has been defeated.And is the Final Boss.	⛔	✅
Lunatic Cultist - HARDMODE		Post-Golem boss summoned by killing the Cultists that spawn at the Dungeon's entrance after Golem is defeated. Defeating the Lunatic Cultist initiates the Lunar Events.	⛔	✅
Queen Slime - HARDMODE		Gelatin Crystal - Spawned only in the Hallow by using a Gelatin Crystal—The crystal is consumed upon use, immediately summoning the boss. The Gelatin Crystal can be found in the Underground Hallow among Crystal Shards growing on Pearlstone. After killing Queen Silme, Just Desserts will unlock.	⛔	✅
Deerclops		Deer Thing - It can be summoned by consuming a Deer Thing at any time of day but only inside of a Snow or Ice biome. After killing the Deerclops An Eye For An Eye will unlock.	⛔	✅

All images from the Official Terraria Wiki.Once all 13 bosses ( PS3/PS VITA ) 15 bosses ( PS4 ), excluding Empress of Light & Queen Slime & Deerclops have been defeated ( can be in separate worlds, but must all be beaten with the same character ), the Trophy will pop. It will not pop if you defeat the Bosses in someone else's world on the PS4 Version.