http://212.67.202.164/~mrbump/rpg/src/religion/myrkul.html
Also: "MYRKUL (MERR-kool)
Lord of Bones, Old Lord Skull
God of the Dead, Wasting, Decay,
Corruption, Parasites, Old Age,
Dusk, Fall, Exhaustion NE
Greater Power Hades
Symbol: A skull or skeletal hand
NOTES: This god usually appears as a cloaked, animated corpseóskeletal at its head, becoming fleshed toward its feet, which are gangrenous and rotting. Myrkul is said to have a cold, malignant intelligence and to speak in a high whisper His supernatural servants are known as ìDeathsî (such as that which appears as part of the deck of many
things, DMG, p.143). He can animate and command the dead, but has no power over undead above the level of zombies and skeletons. Myrkul lives in the Castle of Bones, located in a moonless Land of Always Night (Hades)."
Lots out there on the web, but nothing compellingly complete.
Greg