Born in Palo Alto, California, McGill became interested in magic as a child (and was later considered legendary in magic circles), but first studied hypnosis in 1927 while still a teenager. He wrote the seminal Encyclopedia of Genuine Stage Hypnotism (the acknowledged bible of stage hypnotism) in 1947, and continued to teach courses and lecture right up until a few days before his death. He died in his native Palo Alto.
From 1947 to 1954, McGill performed hypnotism and magic under the stage name of Dr. Zomb. His "Séance of Wonders" show featured horror-themed routines and costumed assistants typical of the midnight "Spook Shows" which were popular during that era.
In addition to his career as a world-traveling magician and stage hypnotist, McGill was also a skilled hypnotherapist and a student of Eastern mysticism. He wrote between twenty-five and forty books (sources disagree on the total), including such titles as Grieve No More Beloved (about his afterlife contact with his deceased wife), Hypnotism and Mysticism in India, and his autobiography, The Amazing Life of Ormond McGill.