List of Marvel Comics characters: I

Icarus (Joshua "Jay" Guthrie) is a mutant superhero. He was a member of the student body at the Xavier Institute and a member of the New Mutants training squad. Jay was the son of Thomas and Lucinda Guthrie. Thomas dies early in Jay's life due to black lung, developed from working in local Kentucky coal mines. Jay's older siblings Sam (Cannonball) and Paige (Husk) are mutants as well, and both have been members of the X-Men. When he himself developed mutant powers, he hid them from his family. However, when performing in his band, playing guitar, he exposed his wings to the crowd as a 'stage gimmick'. Believed to be descended from the ancient race of Cheyarafim mutants. Icarus possesses red-colored, feathered angel-like wings which allow flight and produce extensive regenerative enzymes allowing him to recover from normally fatal injuries. However, this healing factor comes from his wings; when his wings were removed, he lost this ability. His voice is capable of producing sonic frequency beyond the range of human capability as well as creating multiple sounds or voices at once.

Idunn is an Asgardian. The character, based on the Iðunn of Norse myth, was created by Stan Lee and Jack Kirby, and first appeared in Journey into Mystery #114 (March 1965). Within the context of the stories, Idunn is the Asgardian goddess of immortality. She appears as a supporting character of Thor.

The Iguana is a supervillain, an enemy of Spider-Man. The character, created by Bill Mantlo and Jim Mooney, and appeared in Peter Parker, The Spectacular Spider-Man #32-34 (July–September 1979). Within the context of the stories, an accident occurs while Dr. Curt Connors experiments on an ordinary iguana, endowing the iguana with part of Connors' lifeforce and memories, as well as the personality and powers of Connors' alter-ego, the Lizard. The Iguana becomes a human-sized semi-humanoid reptile with superhuman strength, hypnotic powers, and the ability to mentally control other reptiles. The Iguana encounters and battles Spider-Man, and is turned back into a normal iguana.