There were a few organizations known as a "Magician Guild".
Another was the Magician's Guild of America in New York City which was a professional magic society started around 1943.
A few IBM rings used the term such as the Magicians Guild of Lansing (Ring No. 54), the Edmonton Magicians Guild (Ring No. 28), and the London Magicians Guild (Ring No. 265) which was formed in London, Ontario, Canada (as a result of a name change from the "London Magic Club").