James is an elite soldier and a member of the Murder of Crows, a team composed of Jacob Kane's old partners in the special forces. He is a sniper with the Navy SEALS and boasts 312 confirmed kills. He also designs and builds self-replicating nanotech, and in his spare time he taught his teenage daughter how to hack into Swiss bank accounts. Marcus also can't stop telling dirty jokes.
Marcus James was created by J.H. Williams III and Haden Blackman in Batwoman #0.