Malbrothax

Malbrothax, or the Steward of Filth, as this thing is known, is believed to be the servant of Nurgle himself, and its appearance always foretells the outbreak of some new and dreaded plague. As the Handmaiden of Nurgle, there are some legends that suggest it is in fact a Greater Daemon who is so powerful it can appear in the Old World at will without being summoned first. Mabrothrax is a large, hulking humanoid with thin spindly arms and legs that end in appendages equipped with razor-sharp claws. Its body is a thin bag of skin filled with a soupy mess of entrails, excrement, and decay. Situated on top of this disgusting torso is a round, searching head dominated by a massive maw filled with sharp jutting teeth. The stink of rot and faeces precedes the manifestation of this apparition.

Attracted By: Magic of Nurgle, Despair, Disease

Source

 * Warhammer Fantasy RPG 2nd ED -- Tome of Corruption (pg. 209).