Captain 3D

Origin
Captain 3D is the last of the people of D, who were exterminated 50,000 years ago by the Cat People (currently led by Tigra). He has been preserved in 2D, within the pages of the Book of D, which has been protected by a human gaurdian since the demise of his own people. The current guardian is Danny Davis who runs a used book shop.

Captain 3D seems to posses the ability to traverse from 2D to 4D. In 3D, his belt is able to use 4D energy to give him the power of flight. He is an exceptional fighter besides that, and he may have knowledge of his people's advanced technology.

Golden Age Appearances
Captain 3D #1