Nemesis is a fictional character in the DC Comics universe. He is a vigilante, turned operative for the U.S. government and a master of disguise. He uses disposable masks made of a fine, highly malleable material which could be instantly dissolved with a special spray that he kept concealed in his collar. He first appeared in The Brave and the Bold #166.

Tom Tresser was an applicant to an unnamed government agency whose brother Craig was an undercover agent infiltrating a criminal syndicate called the Council. Craig was brainwashed into killing their family friend Ben Williams and was subsequently killed in self-defense by fellow agents. Tom thus became the Nemesis, preferring to use an alias instead of his dishonored family name. With the assistance of Batman, he cleared his brother's name and saw the men responsible for his death dead. Nemesis was apparently killed in the helicopter crash that killed the Council's leader, though he was later revealed to have survived. He then became one of the few non-criminal members of the Suicide Squad. After his involvement with the Suicide Squad ended, he apparently met his end - again - in the pages of Catwoman.

Nemesis is not to be confused with Holocaust, a Marvel Comics character who has also gone by the name of Nemesis, or with Nemesis Kid.