The Cult of Pleasure was an Elven Chaos Cult centred around the worship of Slaanesh, the Chaos God of pleasure in the time before the Elven civil war known as the Sundering. The cult was founded and lead by Morathi the mother of Malekith and for a long time was seen as merely a society of painters, musicians, actors, poets and other artists centred around the acquisition and production of great works of art. The cult had been formed because Morathi had been influenced by previously being captured by Chaos forces dedicated to Slaanesh.
Eventually the cult was exposed for what it was, a front for the worship of Slaanesh, and Malekith himself took charge of the inquest to root out and destroy Chaos worshippers in the cult. Because of this advantageous position, and his lust for the throne, Malekith accused the Phoenix King Bel Shanaar of being a worshipper of Slaanesh. When the Council of Princes did not agree and refused to have Bel Shannar executed, Malekith poisoned the King and attempted to claim the throne - only to be horribly burnt in the Flames of Asuryan.
After the Sundering, The cult was outlawed by both the High Elves of Ulthuan and in Naggaroth by the Witch King of the who decreed that Dark Elves should worship only Khaine, Elven god of war, bloodshed and murder. In recent times the cult is undergoing a revival, again under the leadership of Morathi. It is possible Malekith turns a blind eye to this as he and his mother are rumoured to have an incestuous relationship.
It is not known if the cult will play a part in the storyline of Warhammer Online.