The Malfera is a creature from the Nightmare Dimension that is only encountered on the Prime as the result of a powerful summoner.
It first appeared in module X-5, pg. 28.
Companion Rules Set, pg. 34
Rules Cyclopedia, pg. 191
Savage Coast Monstrous Compendium, available on the Vaults of Pandius
Creature Catalog V, Sean K. Reynolds, Dragon 343, pg.51 ?
pictures: From SCMC & From Steve Ellis in Dragon
Monstrous DB for OD&D
3e stats by Travis Laney 2007
3e stats by Valentius July 2005
See its Monster Lore entry by Gary Davies June 2007
4e stats by John Walter Biles Jan. 2009