The Evil Twin Game

Name the evil doppelgangers of various heroes in personality and / or powers / abilities.
i.e.
Spider-man and Venom
Venom and Carnage
Wolverine and Sabertooth
Preferrably in-comic doppelgangers but it can also cross-company lines.
i.e.
Batman and Green Goblin.

Batman and Green Goblin??? Sure they're both rich, but does that make Black Panther or Xavier their foil too?

Wolverine - Lady Deathstrike
Superman - too many to list
Anyone with the name "Dr." in their name - every other "Dr."
Green Lantern - Quasar
JLA - Avengers - Ultimates - Authority

Deathstroke - Deadpool
Mr. Fantastic - Elongated Man - Plastic Man
Darkseid - Thanos

Robin .... Bucky

Superman- Bizaro Superman
Batman- Rha's Al Ghul
Phoenix- Dark Phoenix
Dr Strange- Baron Mordo

Scarlet Spider- Kane
Kane- Spidercide
Witchblade- Excalibur
Banshee- Syrin
Batman- Joker

Jubilee...?

Batman- Prometheus

Talking of Evil-twins, at the end of Amazing Spider-man 522, Spider-man has to confront Hydra's version of Cap, Thor, Iron-man and Hawkeye.................