Mercury

Cessily Kincaid is a mutant whose body transformed entirely into living liquid metal, leaving her with a malleable, silvery form she can reshape at will. She enrolled at Xavier's Institute, becoming part of the school's student population in the X-Men's corner of the Marvel Universe.

Introduced in the pages of New Mutants #10 in 2004, Mercury is a Modern Age Marvel creation from the creative team of Nunzio DeFilippis, Christina Weir, and Carlo Barberi — and she's been a steady presence in the X-Men corner of the Marvel Universe ever since. With over two decades of publication history stretching from 2004 all the way to 2026, she's proven herself a genuine fixture of the young mutant scene, appearing most prominently in New X-Men, New Mutants, and X-Men: Pixie Strikes Back. She keeps remarkable company — sharing adventures with heavyweights like Wolverine and fan-favorite student characters such as Rockslide (Santo Vaccarro) and Victor Borkowski — and three of her appearances carry key-issue status, making her a name collectors have quietly learned to watch for. If you love the rich, character-driven era of Xavier Institute storytelling, Mercury is absolutely worth tracking down.