James Herbert Brennan (born 5 July 1940) is an Irish writer of fantasy literature and occultism.

His most known work is the book titled "Occult Reich", published in 1974. The book explains various aspects of the Ariosophy. Brennan is also the author of the quest game The search for the Grail, published in the 1980s. He sold millions of copies worldwide of this quest game, mainly in France.