S.L. Macgregor Mathers
Samuel L. MacGregor Mathers (1854-1918) was a British occultist. 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 today. He became so synonymous with the order that Golden Dawn scholar Israel Regardie would in retrospect observe: "the Golden Dawn was MacGregor Mathers."