English occult order, founded after the breakup of the Hermetic Order of the Golden Dawn in 1900 by former GD head Samuel Liddell Mathers and his supporters. There were two temples in Great Britain, one in London and the other in Edinburgh. The former Golden Dawn temples in the United States—Thme No. 8 in Chicago and Thoth-Hermes No. 9 in New York City—sided with Mathers during the breakup and became part of the Alpha et Omega afterwards. Three other American temples were founded after the First World War: Ptah No. 10 in Philadelphia in 1919, Atoum No. 20 (sic) in Los Angeles in 1920, and Themis No. 30 (sic) in San Francisco in 1921.

The history of the Alpha et Omega is uncertain at best, as few documents survive. All of the temples of the order appear to have gone out of existence by the Second World War.