I realize that there is a large chance that none of these characters, let alone one of them, will ever make it as DLC but hey, one can dream right? Here's my dream list of DLC characters, with characters I particularly want bolded. Type in yours in the comments.

Marvel

Venom (Flash Thompson version)

Songbird

Spider-Woman

Invisible Woman

Green Goblin

Elektra

Chase Stein

Mister Sinister

Gambit

Black Panther

Psylocke

Iceman

Capcom

Mega Man (Mega Man series)

Juri Han (Street Fighter series)

Demitri Maximoff (Darkstalkers series)

Roll. EXE (Mega Man: Battle Network series)

Jin Saotome (Cyberbots: Full Metal Madness)

Ibuki (Street Fighter series)

Nero (Devil May Cry 4)

M. Bison (Street Fighter series)

El Fuerte (Street Fighter series)

Captain Commado (Captain Commado)

Cammy White (Street Fighter Series)

Remy (Street Fighter III: 3rd Strike)

Pyron (as boss that would appear at the end of Galactus Mode) (Darkstalkers series)