Nemesis is a name shared by several characters from the Marvel Universe.
Nemesis (Mr. Kane)
The dishonest owner of Kane Construction, whose well-earned reputation as a slumlord came from his use of cheap building materials. Stealing a suit of armor from the Brand Corporation, Kane became Nemesis and planned to destroy his latest building, collecting on the insurance. He was stopped by the Falcon.
Nemesis (Edward Stanford)
The District Attorney of Phoenix, Arizona, who masqueraded as the crime boss "Nemesis" in a bid for wealth. His schemes were inadvertently ruined by Stanford's wife, Ann Dodgson and her twin sister Clare, who had been transformed into a pair of Captain Universes. In an attempt to "rescue" Stanford, whom Nemesis had "kidnapped," the Captains uncovered his deception.
Nemesis (Gamma Flight)
Her true name is unclear- it may be Amelia or St. Ives- but in the early 20th century, she swore vengeance on her father- Deadly Ernest- for the accidental death of her mother. Using science and magic, she created the Onyx Blade- capable of slicing through nearly any substance, and capable of using the life force of those slain by it to extend her own. With that weapon, she became Nemesis.
At one point, she led the Children of the Night. She eventually intervened in a battle between Alpha Flight and her father, slicing him to pieces. However, when Ernest was revived by Scramble, she returned to help Alpha Flight battle him, preserving their lives with the energies of her father's previous victims. Puck was able to slay Deadly Ernest using Nemesis' blade, and she left again.
Pretending to be her own successor, she became the leader of Gamma Flight until its disbandment, and later helped Wild Child become Weapon Omega. She helped Alpha Flight on a few occasions, until she was forcibly drafted to help rescue the original team by Sasquatch, who bound canotechnology to her and used a device attached to her spine to control her. She opted to stay after the rescue was successful, and eventually convinced Sasquatch to remove his restraints on her.
Nemesis (Infinity Gems)
Being created when the Ego Gem was reunited with the other Infinity Gems. Nemesis, possessed of vast power, warped reality, temporarily creating the Sketch World- a bizarre fusion of Earth-616 and Earth-93060 (the Ultraverse). However, her efforts to further alter existence to her desires were disrupted by the intelligences within the Gems other than Ego. Eventually, Nemesis was battled by Ultraforce and the Avengers, and on the verge of wiping out existence, she was destroyed by the Black Knight. However, the Infinity Gems broke off to become their own beings, while Nemesis' uncontrolled power warped the Ultraverse drastically, until the Reality Gem and Time Gem stabilized things.
Series of ten robots created by Dr. Horatio Belgrade for SHIELD. They were designed to use elements of Cable's techno-organic virus. Unfortunately for Belgrade, upon implanting the virus in the robots, six were destroyed, and the other Nemesis robots went berserk- believing themselves to be Sgt. Fury and his Howling Commandos, and seeing the agents of SHIELD as Nazis. Cable teamed up with SHIELD to destroy them.