Jim Shooter, Marvel's then Editor in Chief, initially came up with the idea for this project, envisioning a guide detailing statistics much in the manner of those found upon the backs of baseball cards. This initial project was to be called The Marvel Super-Specifications Handbook. He appointed Mark Gruenwald editor of the project, and in Gruenwald's hands the project gained its published name and also grew in scope to cover all aspects of the Marvel Universe, although Gruenwald himself noted it was not comprehensive.
The OHOTMU detailed the more significant characters, items and locations in the Marvel Universe, itemizing them into individual entries. Individual entries consisted, in most cases, of:
* A frontal full-body view of the character. These illustrations were drawn solely for the OHOTMU, often by the artist most closely associated with the character; for example, the original entries for Elektra and Bullseye were illustrated by Frank Miller.
* Prose text describing the character's origin, powers, and other abilities and unique traits, as well as 'statistics' such as place of birth, former aliases, height, weight, hair and eye color and so forth. The original edition opted only to describe the "Origins" of characters (how they acquired their powers), instead focusing heavily on detailed explanations for how those powers functioned. In its Book of the Dead supplement, however, the handbook provided entire "Histories" for the deceased characers, a trend which was then adopted for the main body of the Deluxe Edition, allowing the entire life and career of the characters to be covered. In a few cases, the Handbook even included previously unrevealed information. In addition, major important pieces of equipment were given technical illustrations with breakdowns of their functions and features.
* Example pictures of the character in action, taken directly from the comics themselves.
There have been many iterations of the OHOTMU concept since it was first launched in 1982, this torrent features:
Volume II, 1989: the OHOTMU Update '89 was published, an 8-issue series. This series is notable for including numerous non-superhuman supporting characters, where previous runs had all but neglected them.