Ordo Templi Orientis (OTO) is a worldwide religious and fraternal organization. It was founded in Germany at the turn of the 20th century by Carl Kellner and Theodor Reuss. Once associated with European Freemasonry, the OTO is now best known for its ties to Aleister Crowley.
The Hellfire Club refers to a collection of exclusive societies founded in Britain and Ireland in the 18th century. These clubs were mainly attended by aristocrats and other wealthy people, and they were predominantly identified with high society. The Hellfire Clubs were known for their excess, which included binge drinking, gambling, and other types of scandalous and immoral activity. The clubs were also notorious for their secrecy and alleged ties to the occult, which added to their notoriety.