First Appearance: USA Comics #7 (February 1943).
Golden Age Appearances: USA Comics #7.
Modern Appearances: None.
Years Active: 1943-?
An ordinary schoolboy named Martin Burns is visiting a museum with the other students from his school when a mummy case falls and wounds him. The "extract" (ewww) of the entombed mummy seeps out of the mummy case and into Martin's open wound. And since the mummy was actually Hercules (don't ask), well, you know that zany whackiness is going to ensue.
Sure enough, that night a mysterious Shadow (not the Shadow--a Shadow) visits Martin and tells him that he now possesses the spirit of Hercules. (He got it via the "extract," see?) Martin, not needing to be told more than that, puts on a costume (where it comes from is never made clear) and becomes the crime-fighting hero Marvel Boy (II).
Marvel Boy (II) has the strength of Hercules, the speed of winged Mercury, and the wisdom of Abe Lincoln.
Note: There is, of course, an obvious Captain Marvel influence on Marvel Boy (II). There is also the curious case of Marvel Boy (I). MB (I) has the same name as MB (II). He has something of the same background. (II)'s story could be a redrawn (I) story taken from inventory. But (II)'s powers are different and his origin is somewhat different, and why redo the origin so substantially? So I'm going to assume that both exist in the same continuity and that the similarity in names and origins is just a coincidence.