Ringo Starr was the drummer for the Beatles. (COMIC: Signs of Life)
The Doctor once gave him the number for the TARDIS telephone. In his eighth incarnation, the Doctor assumed it would be Ringo calling when Winston Churchill contacted him, as very few people had the number. (AUDIO: Their Finest Hour)
When taking Amy to see the Beatles, the Eleventh Doctor wondered why no one wished to see Ringo, to which Amy replied, "There is no such thing as a sexy drummer". (GAME: City of the Daleks)
In 1964, Andrea Yates told Sarah Jane Smith that she wanted to make loads of money, marry Ringo Starr and move to Saint-Tropez. (PROSE: Whatever Happened to Sarah Jane?)
At some point, the Tenth Doctor took Donna Noble to see the Beatles play "My Bonnie" at The Cavern Club. (COMIC: The Time of My Life)
Alternate timeline
In an alternate timeline created by Lenny Kruger in which the Common Men rose to prominence in place of the Beatles, Starr never pursued a musical career. Unlike the other potential Beatles, however, he was not enlisted in the British Army as part of national service due to health problems. (AUDIO: 1963: Fanfare for the Common Men)