Modok: Formerly an ordinary human, George Tarleton was transformed into a Mental Organism Designed Only for Killing (M.O.D.O.K.) during an experiment by Advanced Idea Mechanics (A.I.M.). Calling himself the Scientist Supreme, he is capable of various types of attacks and also has superhuman calculating ability.

Akuma: Akuma is a fighter who took on the name of "Master of the Fist," and seeks a true battle to the death with Ryu. While his basic fighting style is based on Ansatsuken, the same as Ryu, Akuma seeks to lead Ryu down the path of his own fighting style, the "Satsui no Hadou," in order to make him into a worthy opponent.