The Fiends of Slaanesh, also known as "Beasts of Slaanesh," "Hunting Beasts of Slaanesh," "Rams of Slaanesh," "Bestials," "Unholy Ones," "Chimerial Leapers," and "Fiends of Exaltant Excess" are Lesser Daemons of Slaanesh, the Chaos God of pleasure and pain, spawned directly from the mad mind of the Serpent. Like most Chaos Daemons they appear in all 3 of the Warhammer settings.
https://warhammerfantasy.fandom.com/wiki/Fiends_of_Slaanesh