This was a limited series
of magazines published by Marvel Comics
in the early 1980s, providing a comprehensive encyclopedia
to major and minor characters (both living and dead
), places, and unique weapons and vehicles from the Marvel Universe
. In the mid-80s it was superceded by the "Deluxe Edition", and then "Update '89". Marvel has promised another update from time to time, but it has never materialized.
In the 80s and early 90s, the Handbook was the definitive reference when arguing about what a character could or could not do. Since the Update '89, however, so much has changed in the Marvel Universe that the Handbook is now considered unreliable by fans.