Shadow is an original character in the game Marvel Super Heroes VS Street Fighter. He is Charlie after being captured by M. Bison and brainwashed, becoming his slave, yet redeemed afterwards. He was a palette swap of Charlie, with nearly his entire body blacked out, and a white eye shining behind his glasses. He had all of Charlie's moves, but his attacks would set his opponent alight with blue Psycho-Power flames. His supers also had a brief pause where his eye would gleam before the move was pulled off (this made him somewhat unpopular, as the gleam could give an opponent enough time to block or avoid the attack). He has a new level 3 Hyper Combo, Final Mission, and is faster than Charlie.
The Marvel vs. Capcom series provided a twist on Charlie's fate. In his ending for X-Men vs. Street Fighter, Charlie is captured by Bison, who performs terrible experiments on him. Charlie's fate would be left up in the air until Marvel Super Heroes vs. Street Fighter, where a secret character by the name of Shadow appeared. Shadow would later appear in Marvel vs. Capcom as a secret helper character. However, by Marvel vs. Capcom 2, Shadow seems to have reverted back to his original form, but by how is unknown. He makes a cameo in Shadow Lady's ending, where they see an unconscious Jin Saotome after a battle against M. Bison and eventually turned the latter into "Shadow Jin". In this same ending, its shown that both Shadow and Shadow Lady have defected from Shadowloo, as they were trying to save Jin from M. Bison, but arrived late.