Brennan also authored numerous other books covering many subjects including history, the occult,
New Age, self-improvement, parapsychology, and several romance novels. In 1995 he contributed two novels to the
Horrorscopes novel series under the house pen name "Maria Palmer". In 1998 he published
Martian Genesis an
ancient astronaut book which claimed the human race is of
extraterrestrial origin. In 2003, Brennan published the children's book ''The Book of Wizardry: The Apprentice's Guide to the Secrets of the Wizards' Guild'' under the pseudonym "Cornelius Rumstuckle." The book purports to instruct children on how to become a
wizard; it discusses crafts such as making a
wand, and includes
astrological references throughout. According to the biographical note on the back cover, Rumstuckle "joined the Wizards' Guild in 1514 and became its youngest president ever seventy-eight years later, a post he holds to this day." In 2011 Herbie Brennan's book
The Secret History of Ancient Egypt was republished by Bedford Square Books. In all, Brennan wrote more than 100 books, which were translated into 50 languages. ==Personal life==