I saw AS a few years ago. His guitarist (Dave Nachmanoff) called Al the King of Historic Rock. Crowd chuckled a bit. I'd bet over 70% of Stewart's catalog is about historic figures. Also, if simple lists are allowed, Billy Joel's We Didn't Start the Fire has quite many.
Holy moly, I can't believe this thread has gone as far as it has with no mention of Phil Ochs. At least half of the songs on his three Elektra albums (and the Rhino album) are about real people. A few of his A&M cuts are as well:
Ian Matthews: "True Story of Amelia Earhart"; "Amelia Earhart's Last Flight" Johnny Clegg: "Asimbonanga (Mandela)" Fairport Convention: Whole album "Babbacombe Lee" Paul Kelly: "Bradman" (Legendary cricket player) Klaatu: "Sub Rosa Subway" (about the guy who built the New York Subway) The Pernice Brothers: "Ballad of Bjorn Borg" (Famous Tennis Player) Butch Patrick: "Whatever Happened To Eddie" (Song about TV character "Eddie Munster" but sung by the actual actor) Dion: "Abraham, Martin & John" Johnny Wakelin: "Black Superman" (about Muhammad Ali)