What are all the final bosses in the sonic games

Sonic the Hedgehog (Sega Genesis): Four crushers, one of which contains Dr. Robotnik.

Sonic 2 (Sega Genesis): Metal Robotnik

Dr. Robotnik's Mean Bean Machine: Dr. Robotnik

Sonic CD: Robotnik in a sphere with spinning metal plates going around it

Sonic 3: Robotnik with a giant metal claw

Sonic & Knuckles: Metal Robotnik

Sonic 3D Blast: Miniature Death Egg

Sonic Adventure: Perfect Chaos

Sonic Adventure 2: Biolizard

Sonic Heroes: Metal Sonic Monster

Sonic Unleashed: Dark Gaia