Captain Marvel Jr., from Master Comics #30, September 1942. Art by Mac Raboy.

Captain Marvel Jr. is a fictional character, derived from the DC Comics (formerly Fawcett Comics) character Captain Marvel.

Captain Marvel Jr. was an orphaned newsboy named Freddy Freeman who was fatally wounded in a battle between Captain Marvel and his enemy Captain Nazi. Marvel transformed into his civilian identity, Billy Batson, and brought the dying Freeman to the wizard Shazam, who had given Batson the powers of Captain Marvel. Shazam granted this wish: when Batson transformed into Marvel again by shouting the magic word "Shazam!", Freeman shouted "Captain Marvel!" and was also transformed. Freeman, who was now called Captain Marvel Jr., resembled a younger Captain Marvel, though with a yellow-on-blue costume with a red cape, rather than Marvel's yellow-on-red with a white cape. Whenever Freeman says the magic words "Captain Marvel!" he transforms into Captain Marvel Jr. or returns from that form to that of Freddy Freeman. However, as a result of Captain Nazi's near-fatal attack, Freddy is permanently lame in his left leg (although Captain Marvel Jr. bears no such impediment).

When DC Comics bought out the Marvel Family in the 1970s and merged them into the DC Universe in the Crisis on Infinite Earths, Captain Marvel Jr. went as well. As a part of the unified DC Universe, he became a member of the Titans for a time, calling himself "Captain Marvel" or "CM3".