Separated at Birth

Evil Willow from season six of
Buffy the Vampire Slayer

Ozzy Osbourne

The Wampa from The Empire Strikes Back

The Bumble from Rudolph the Red-Nosed Reindeer

Son of Godzilla

Gary Coleman

(This one was blatantly stolen from http://www.stomptokyo.com)

Lurch

John Kerry

(This one was blatantly stolen from http://www.addamsfamily.com)

Saturn's moon Mimas

Death Star

Thank you NASA

Patrick Swayze
and
Jennifer Grey

Derek Jeter
and
Gary Sheffield

Nobody puts Jeter in a corner.