A cartoon within the Ultimate Universe, starring the voice of James Rhodes, telling the fictional and over-the-top origin of Iron Man. The cartoon was aired in Spanish and was sold in 87 Territories. Rhodes' name and likeness was owned by Stark International and he never made a single cent.
- Prior to being given an official reality number, this universe was known as Earth-TRN152 as part of our Temporary Reality Numbers classification system.
- The two mini-series Ultimate Iron Man and Ultimate Iron Man II were originally the in-continuity origin of Ultimate Iron Man, however this story was later retconned by Mark Millar by revealing that it was actually a cartoon within the Ultimate Universe that was commissioned by Tony Stark.
- 12 appearance(s) of Earth-55921
- 48 image(s) of Earth-55921
- 22 characters that originate from Earth-55921
- 1 teams that originate from Earth-55921
- 3 organizations that originate from Earth-55921
- 2 locations that originate from Earth-55921
- 1 items that originate from Earth-55921