The crossword solution for the term 'Frosty Marvel Mutant' is 'Iceman'. Iceman is a fictional superhero appearing in American comic books published by Marvel Comics. He was created by writer Stan Lee and artist Jack Kirby, and first appeared in The X-Men #1 in 1963. Iceman is a mutant who has the ability to manipulate ice and cold. He is one of the founding members of the X-Men and is considered to be one of the most powerful mutants in the Marvel Universe.