Captain 3-D

Within the comic's fictional biography, around fifty thousand years ago a war occurred between two civilizations: a humanoid people and a race of Cat People (the Cat People later had their continent sink). Professor Five, a humanoid scientist, devised a method to preserve 'the Chosen One' of his people in a 'two-dimensional half life' inside a specially prepared volume called the Book of D so that the Chosen One could be released in the future to oppose the Cat People. Professor Five is described as having been killed afterward; the Book of D is entrusted to successive human guardians in the modern era until Danny Davis finds it in a bookshop, discovers a pair of strange glasses inside, and — by looking at an illustration through the glasses — releases the illustrated man who 'springs to life off the page.' These elements are presented as the character's in-universe backstory in the single published issue (cover-dated December 1953).

The comic's textual descriptions report a found illustration of 'a strangely dressed man' inside the Book of D who, when viewed through the special glasses, appears to spring off the page. The supplied sources do not provide a detailed verbal description of costume, coloration, or precise visual features beyond that phrasing; visual specifics are available only in the comic artwork itself.

As presented in the comic, Captain 3-D is gifted with superior intellect and physical attributes — described as 'fitter, stronger and faster than normal humans' — and can survive for millennia stored within the Book of D. His manifestation is episodic: he is kept in two-dimensional stasis and can be released for brief periods when someone views the book's illustration through the special glasses Professor Five built. In modern incidents he acts as a protector/guardian of the Book's human keeper and subdues attackers; the glasses also reveal disguised Cat People among humans. The precise limits, duration of release, and detailed power levels are unspecified in the character's single brief appearance.