Giant-Size X-Men #1 was a one-time issue of the X-Men comic book series, published by Marvel Comics. It was written by Len Wein and illustrated by Dave Cockrum. Though not a regular issue, it jumpstarted the series after a five-year long hiatus. The issue serves as a link between the original X-Men and a new team. Chronologically it is placed before The X-Men #94. The 68 page issue was published in May 1975.
The story-line links the old X-Men team with the new. In it, the old team (Cyclops, Marvel Girl, Angel, Iceman, Havok and Polaris) venture to the island of Krakoa and vanish. Cyclops is allowed to return to tell Professor X what has happened. This prompts the professor to assemble a new team of X-Men to rescue the old. The new team includes Sunfire and Banshee, who were actually introduced in earlier issues. The team also includes all new members that never appeared before in an X-Men comic, including Storm, Nightcrawler, Colossus, Thunderbird and Wolverine (who actually made his first appearance in the Marvel Universe in The Incredible Hulk #180).
The team soon learn that Krakoa is not just an island, but a giant mutant as well. They are successful in rescuing the old X-Men as well as destroying the island by shooting it into outer space with Polaris's power, despite hiccups in their first time working together. The issue ends by posing the question of the future of the 13 X-Men.