Mesmero successfully took control of large numbers of latent mutants, and captured Lorna Dane. Mesmero was then revealed to be the aide to Magneto, and battled the X-Men in the city of the Demi-Men. Mesmero's master was later revealed to be a robot in the form of Magneto, and a Sentinel attack resulted in Mesmero being captured by Sentinels. Much later, Mesmero had become a carnival manager and mentally compelled the X-Men to serve as carnival performers. The X-Men freed themselves from his control, and as Mesmero then attacked the X-Men, the real Magneto appeared. The Master of Magnetism overpowered Mesmero and rendered him unconscious. Magneto then stranded him in a South American jungle.
Mesmero later performed in a Broadway stage show in New York City, where he battled Spider-Man. Mesmero later escaped to Canada. There, he contended with Alpha Flight and was captured by Persuasion. Mesmero later posed as a psychoanalyst to powerful clients in London. He took control of Excalibur and used them to battle Fenris. Mesmero was defeated by Lockheed the dragon and students from St. Searle's School for Young Ladies.
Mesmero has encountered the X-Men on a few other occasions as well as teams such as X-Factor, and the Dark Riders. The Dark Riders intentended to kill him, as they believe he was weak. Mesmero uses his powers to convince them they had thrown him off a high ledge. With Alpha Flight, Mesmero takes over the minds of the juinor members and is eventually stopped by the senior ones.
When Mesmero joined the latest incarnation of the Weapon X program, the Director offered to increase Mesmero's hypnotic powers. Mesmero agreed and gained the ability to control entire crowds with a mere glance, instead of a mere handful of people.
To keep the public unaware of the "Neverland" mutant concentration camp, Mesmero posed as a government liaison. With this identity, he informed news reporters that "Neverland" doesn't exist nor is the government involved in abducting mutants.
While he was a member of Weapon X, Mesmero visited his dying mother. He had doctors help her as much as they could and used his powers to mesmerise his mother into believing she was healthy as ever. His mother knew it was an illusion, though, and she told him that she knew shortly before she died. Subsequently, Mesmero began to lose confidence in himself which caused him to lose his powers. Mesmero was transported to Neverland upon the Director's discovery of his power loss.
Brent Jackson, planning on raising a coup on Weapon X, rescued Mesmero. Mesmero spent several months in seclusion as Jackson helped him get his confidence back, and with it his powers.
Ironically, Mesmero eventually lost his powers for good (along with most of the world's mutants) when the Scarlet Witch altered reality at the climax of the House of M event. Devastated and ruined, the once-great supervillain was forced into poverty.
Mesmero finally achieved a personal triumph by forming a relationship with a woman who had saved his life, promising to somehow help her in turn. She put her trust in him freely and unconditionally, something he had never managed before without the aid of his powers. At this, Mesmero resolved to put his past behind him and begin living as Vincent.
Mesmero's green skin, once believed to be a mask, is apparently his real skin color. It is not known if he was born this way, or if it developed later in life along with his powers.
At one time, Mesmero wore a costume which allowed him to teleport, leaving only a blip of energy where he once stood. The feat was only used to escape an angry Alpha Flight, and may have been controlled entirely by the technology of the suit, or may have been tied in some way to his mental abilities.
In Exiles #85, another alternate version of Mesmero was reveled to have existed on Earth-127. This Mesmero was part of the Brotherhood of Mutants alongside Magneto, Quicksilver and Scarlet Witch (all gender-swapped, with Scarlet Witch now being called Scarlet Warlock). They planned to make Magneto (who was female in this reality) even powerful than she already was by removing Wolverine's adamantium skeleton out of his body and transfer it into Magneto's body. However the plan went wrong, and Mesmero and the other Brotherhood members fused into one powerful mutant being known as "Brother Mutant".
In the X-Men: Evolution animated series, Mesmero used several members of the young X-Men (Jean Grey, Nightcrawler, Spyke and Shadowcat) to steal three rings. The three rings connected together with a golden rod to form a key that would open the first of three doors sealing away the oldest and most powerful being of all time... Apocalypse. He was eventually discovered by Professor X and Rogue, but, despite Rogue using Jean's powers and the Professor launching a telepathic assault, Mesmero escaped and opened the first door.
After using Gambit to steal half of a spider stone, Mesmero had a run-in with Magneto. Magneto and Mastermind attempted to probe his memories and find out who he was. When Magneto found out about the spider and the doors, he did everything in his power to stop Mesmero. The second half of the spider stone was found in a museum. When Magneto put both halves of the spider stone together, a giant green spider appeared. It turned out that the spider stone was the key for the second door. Mesmero was able to trick Mastermind and, when Magneto destroyed the spider, he ended up opening the second of three doors that contains Apocalypse.
With only one door left, Mesmero was closer than ever to his goal. He tricked Mystique into helping him, telling her that she and Rogue would be safe if they helped him to release Apocalypse. Mystique believed him and was sneaked in as the key to the third door. Mystique turned into a snake and went through a hole in the door and touched the symbol of Apocalypse causing her to turn to stone. Apocalypse was released. But it seems all of Mesmero's loyalty was for nothing, because when Apocalypse forced his way past the teams and gained his freedom, he left Mesmero behind. He was voiced by Ron Halder.
This version of Mesmero has a different look from his comic-book counterpart but is more powerful and more adept at hand to hand combat than his comic version. He is bald, his face is heavily tattood and speaks with a Middle-Eastern accent. The majority of his power is implied to come from Apocalypse, as opposed to his own, and the show never specifies whether he is a mutant or a normal human. Prior to the release of Apocalypse, even Professor Xavier has a hard time matching his mental powers. However, once discarded by Apocalypse, Mesmero is easily captured by Wolverine and Jean Grey, and can offer little resistance when interrogated by Xavier.