Jack Biceps was a kid who hated superheroes, so much so that he set out to become "Evil's Own Superhero" to oppose them. As Sinistro, Boy Fiend, he used his not inconsiderable intellect in various attempts to assist the underworld against the likes of the Blue Beetle and Peacemaker, but somehow he never seemed to have much luck and his efforts were largely unappreciated.
- Sinistro shared continuity with Blue Beetle and Peacemaker, so he presumably would have been among the Action Heroes characters that DC purchased from Charlton in 1983. Nevertheless, he has yet to appear in any comic published by DC Comics.
- This version of Sinistro, Boy Fiend, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- 1 Appearances of Jack Biceps (Earth-Four)
- 1 Images featuring Jack Biceps (Earth-Four)
- Quotations by or about Jack Biceps (Earth-Four)
- Character Gallery: Jack Biceps (Earth-Four)