To be honest, I know there's a million options to choose from but this idea came to mind and think it has more possibilities then a standard 'this guy & this guy' topic.
The topic of Amalgam Contest# 80:
So here's the deal...The participating artists can combine any 2 characters they want, so long as the characters are each other's arch nemesis. An example? Superman and Lex Luthor. Not Toy Man, not Parasite. You pick a hero and then the one enemy that completes them. And sure, some characters have more then one prominent bad guy that could fit that bill (I'm lookin' at you Spider-Man).
As always, multiple entries are encouraged but the vote still comes down to the single entry with the most votes.
@shatterstar - can you please pin this?