Doctor Nemesis is the name of two fictional characters appearing in American comic books published by Marvel Comics and Ace Magazines. The first is James Bradley, a superhero and associate of the X-Men, while the second is Michael Stockton, a supervillain and enemy of Ant-Man.

The first version (James Bradley) was a derivative version of the eponymous Golden Age character, that originally appeared in Ace Magazines' Lightning Comics. He is a co-creator of the original Human Torch android, and appears in Uncanny X-Men as a member of the X-Club. Doctor Nemesis appeared in Cable and X-Force, a series by writer Dennis Hopeless and artist Salvador Larroca that debuted in December 2012.

The second version (Michael Stockton) was unidentified in Marvel Feature #4, but officially debuted in Marvel Feature #9 and was created by Mike Friedrich and Craig Russell.

James Bradley was born in San Francisco in 1906. Although primarily trained as a medical physician, he began working in the late 1930s with Phineas Horton in developing the original android Human Torch of World War II. While mostly a silent partner in this endeavor, Bradley began building a second android during this time.

The two scientists did not correct the design flaw that causes their android to burst into flames upon exposure to oxygen. Bradley had preferred they resolve this issue before revealing their work to the public. Horton, eager for fame and further financial backing, held a press conference in late 1939 debuting their work. This turned into a public relations disaster, as Bradley had predicted, when the android caught on fire, causing the press to label it a menace. Bradley broke off their partnership thereafter and took his unfinished second android with him.

Sometime before 1941, Bradley completed his work and the second android acted as the superhero Volton from late 1941 to early 1942. Unaware of its artificial origins, Bradley led Volton to believe it was a scientist named Guy Newton who had discovered how to generate electricity. Around this time, Bradley also decided to become a masked crimefighter, too. While working by day at Mercy Hospital in New York City, he would don a surgical mask to fight corruption and crime as Doctor Nemesis.

According to Jess Nevins' Encyclopedia of Golden Age Superheroes, Bradley "uses his fighting ability and hypodermic needle full of truth serum to fight gangs and costumed madmen like the hypnotic Swami, the Surgeon (who unleashes plague-bearing rats on the city), and Dr. Quartz, the comic book version of the sociopathic vivisector who was Nick Carter's arch-enemy in the dime novels."

After a number of adventures, Doctor Nemesis was approached by agents of the Third Reich to form a group of costumed beings. Signifying a change in tactics, Bradley changed his alter-ego to Dr. Death and recruited Human Meteor, Spider Queen, Strongman, and Volton for the group Battle-Axis, which took extreme efforts to force the United States out of participating in World War II. After the war, Bradley reassumes the Doctor Nemesis persona and moves to Santiago del Estero, Argentina to hunt down Nazi refugees.