Giant-Size Fantastic Four Vol 1 #4

1st Appearance of Jamie Madrox ( AKA: Multiple Man)

While taking the subway to a football game with Alicia, the Thing's plans are ruined when Ben has to deal with somebody in a strange costume standing on the tracks. Surprisingly when Ben strikes this man, he turns into two more, and multiplies with each blow. Ben is eventually overpowered and knocked out in a battle. The rest of the FF arrive and revive Ben, but the "Multiple Man" is nowhere to be seen.

The Multiple Man turns out to be Jamie Madrox, a mutant who had the power to create duplicates of himself. However, he had no control over these abilities and so his parents built a suit that would contain and allow him to control his powers. His parents died six years ago and after living that time in solitude, Madrox has found that his suit has begun to malfunction and this is what has brought him to New York City.

The FF track down Madrox and battle him, however his duplicates prove to be too powerful for them to deal with. It's not until the intervention of Charles Xavier (a colleague of Jamie's father) arrives to lend a hand. Xavier explains to Reed Richards of the situation, and while the FF battle Madrox and his doubles again, Charles uses his mental powers to stun them all. Reed then uses his stretching powers to get close enough to the real Jamie Madrox and correct the problem with his containment suit. The process leaves Madrox unconscious, Charles then tells the FF that he will take Jamie into his care and cure him of his madness.