B
- Balder
- Baron Zemo
- Beast (McCoy, Henry "Hank") - dead
- Beetle (unknown)
- Ben Parker (dead)
- Ben Reilly
- Betty Brant
- Betty Ross
- Big Bertha (Unknown)
- Bishop - dead
- Black Bolt
- Black Cat (Hardy, Felicia)
- Black Jack Tarr
- Black Knight (Alex, surname unknown)
- Black Mamba (Sealy, Tanya)
- Black Panther (Udaku, T'Challa)
- Black Widow (Chang, Monica)
- Black Widow (Romanova, Natasha)
- Blacklash (Scott, Marc)
- Blade (unknown)
- Blob (real name Fred J. Dukes) - dead
- Blur (Squadron Supreme)
- Bolivar Trask
- Bombshell
- Boomerang (Myers, Fred)
- Bucky
- Bulldozer
- Bullseye (Poindexter, Benjamin) (only ever known as Benjamin Poindexter)
Read more about this topic: List Of Ultimate Marvel Characters