Vapor

Ann Darnell was one of four civilians who deliberately exposed themselves to cosmic rays during an unauthorized space mission, intentionally recreating the accident that gave the Fantastic Four their powers. The experiment worked — transforming her into Vapor, able to convert her body into any gas.

Vapor burst onto the Bronze Age Marvel scene in 1980, debuting in The Incredible Hulk #254 courtesy of the dynamic creative team of Bill Mantlo and Sal Buscema — and she's been a fixture of the Marvel Universe ever since, racking up 62 catalog appearances across an impressive 45-year span. A proud member of the U-Foes (as well as the Defenders, Alpha Flight, and the Fantastic Four), she keeps remarkable company, sharing adventures with teammates like Vector, X-Ray, Ironclad, and Jimmy Darnell across the pages of The Incredible Hulk and Amazing Spider-Man. Three of her appearances carry key-issue status, a testament to her genuine significance in Bronze Age collecting circles. If you're building a serious Marvel collection with an eye for characters who have real staying power and deep roster credentials, Vapor is absolutely one to track down.