Richard De Mille (born 1922) was a Professor of psychology and an investigative journalist and author.

He wrote Castaneda's Journey: The Power and the Allegory, a book describing the detective work through which he proved that controversial author Carlos Castenada was a charlatan and plagiarist. He edited a second book, The Don Juan Papers, when he found that his exposé did not lead Castenada's most ardent admirers to fall away. This book contained documents representing views of Castenada across the spectrum.

De Mille also wrote a biography of his birth mother, screenwriter Lorna Moon.De Mille's birth father was William Demille, Cecil B. Demille's older brother.Cecil adopted and raised Richard; he did not tell him of his true parentage until William died.

Around this time de Mille became an early convert to the movement that was to become Scientology. But he parted with the movement when the founder took a personal dislike to him.