Samuel Liddell MacGregor Mathers, born Samuel Liddell Mathers, was a British occultist and member of the S.R.I.A.. He is primarily known as one of the founders of the Hermetic Order of the Golden Dawn, a ceremonial magic order of which offshoots still exist. He became so synonymous with the order that Golden Dawn scholar Israel Regardie observed in retrospect that "the Golden Dawn was MacGregor Mathers."

The occult is a category of esoteric or supernatural beliefs and practices which generally fall outside the scope of organized religion and science, encompassing phenomena involving a 'hidden' or 'secret' agency, such as magic and mysticism. It can also refer to supernatural ideas like extra-sensory perception and parapsychology.