Which Beatle was a co-writer on David Bowie's #1 song "Fame"?

David Bowie had spent years shape-shifting through every musical persona imaginable, but by 1975, he still hadn't managed to score a #1 hit in America. He was working on his "Young Americans" album, diving deep into soul and funk while hanging out in New York City studios with some pretty impressive musical company. Which member of the Fab Four helped write "Fame"?