The origins of The Doors lay in a chance meeting between acquaintances and UCLA film school students Jim Morrison and Ray Manzarek on Venice Beach, California in July 1965. Morrison told Manzarek he had been writing songs and, at Manzarek's encouragement, sang "Moonlight Drive". Impressed by Morrison's lyrics, Manzarek suggested they form a band.

Keyboardist Ray Manzarek was in a band called Rick and The Ravens with his brother Rick Manzarek, while Robby Krieger and John Densmore were playing with The Psychedelic Rangers and knew Manzarek from yoga and meditation classes. In August, Densmore joined the group and along with members of the Ravens and bass player Patty Sullivan, recorded a six-song demo in September 1965. This was widely bootlegged and appeared in full on the 1997 Doors box set.

That month the group recruited guitarist Robby Krieger and the final lineup — Morrison, Manzarek, Krieger and Densmore — was complete. The band took their name from the title of a book by Aldous Huxley, The Doors of Perception, which was in turn borrowed from a line in a poem by the 18th century artist and poet William Blake: "If the doors of perception were cleansed, every thing would appear to man as it is: infinite".

-from The Doors on Wikipedia