William Wynn Westcott (17 December 1848 – 30 July 1925) was a coroner, ceremonial magician, and Freemason born in Leamington. He also was a co-founder of the Hermetic Order of the Golden Dawn alongside William Robert Woodman and Samuel Liddell MacGregor Mathers.
Sometime towards the end of the 19th century, Mathers came in possession of the complete volume of the Book of Abraham. He attempted to translate it and was planning to publish the translated version, much to the disfavour of Westcott, who intended to keep its content a secret.
Despite their tensions however, both of them resolved to assassinate Woodman, mostly motivated by fear, since Mathers was able to see "beyond the corporeal," as expressed by Woodman himself, and thus perceived what he truly was. Even though the death of Woodman was decided, Mathers insisted, unlike Westcott, that they could still learn things from their victim.
After the assassination of Woodman, Westcott became the Praemonstrator of the order for five years. After a conflict with Mathers however, he was forced to leave the order, thus leaving the total control to the Imperator.
- Westcott did not find out the truth about Woodman until five years after his assassination. This resulted in a conflict between him and Mathers who kept it a secret.