Who is the Fifth Beatle?

With the recent publication of The Fifth Beatle: The Brian Epstein Story, the Beatle legend takes a “new" turn in the form of a graphic novel. But the notion of a “fifth” Beatle goes back to very beginnings of the band’s origin. In addition to Brian Epstein, the man who discovered and managed the Beatle’s until his death in 1967, a case could be made for each of the following:

Stuart Sutcliffe - The group’s first bass player.

Pete Best - Before Ringo was the greatest, Pete was best.

Neil Aspinall - Longtime road warrior and later manager, Neil played in important part in getting the band off the ground as well building their legacy.

George Martin - As the Beatle’s producer, Martin is responsible in large part for the “Beatle” sound. 

Ed Sullivan - The man who brought and introduced the Beatles to the world in February 1964

 

Billy Preston - The keyboardist who made the Beatles play nice on Let it Be Billy was, with the exception of Eric Clapton on “While My Guitar Gently Weeps” and a variety of session players,  the only musician to play with the band.

Yoko Ono - While perhaps the most controversial choice, Yoko was in the studio during the recording of the “White Album” and clear contributed to a number of John’s tracks.

Who have I forgotten? Who have I left out?
What do you think - could it be Billy Shears?

You tell me. Who else might be considered THE FIFTH BEATLE?