Origin
Aelfric was a twelfth century monk who turned his back on God to devote himself to Satan, and author of the arcane scrolls that became the Darkhold. Burned at the stake in 1149, his spirit lived on to wreak havok in the twetieth century.
Creation
The Mad Monk was created by Gerry Conway and Mike Ploog and first appeared in Werewolf by Night #3 (1972)