This page should only be treated as an accessible, condensed version of good-to-know knowledge concerning the bosses in Cataclysm. The unofficial wiki is more comprehensive and has the full movesets for each boss. Some text here is copied from the wiki.

Sunken City

These are the related bosses to the Sunken City, which can be located naturally or with an Eye of Abyss.

center

Amethyst Crab
Coral Golem
Coralssus
Leviathan

Cursed Pyramid

These are the related bosses to the Cursed Pyramid, which can be located naturally or with an Eye of Desert.

center

Ancient Remnant
Kobolediator
Koboleton
Wadjet

Ancient Factory

This is the only related boss to the Ancient Factory, which can be located naturally or with an Eye of Mech.

center

Harbringer

Burning Arena

These are the related bosses to the Burning Arena, which can be located naturally or with an Eye of Flame. The Burning Arena is only found in the Nether.

center

Ignis
Ignited Revenant

Soul Blacksmith

This is the only related boss to the Burning Arena, which can be located naturally or with an Eye of Monstrous. The Soul Blacksmith is only found in the Nether.

center

Netherite Monstrosity

Ruined Citadel

These are the related bosses to the Ruined Citadel, which can be located naturally or with an Eye of Void. The Ruined Citadel is only found in the End.

center

Ender Golem
Ender Guardian