Is their a finite amount, or is this like asking “songs about love”?
My addled brain can only come up with one right now- that creepy, vaguely- stalkerish, vaguely-homoerotic tribute to the king of late night, “Johnny Carson”, by the Beach Boys:
“Goodbye England’s Rose” is a reworking of “Candle in the Wind” by Elton John
“Buddy X” by Nenah Cherry is about Lenny Kravitz. It was part of a biographical program on Lenny Kravitz, both Nenah Cherry and Lenny Kravitz spoke about it.
“Sweet Home Alabama” – Lynyrd Skynryd (about Neil Young)
“Play it All Night Long” – Warren Zevon (about Lynyrd Skynryd)
“James Dean” – The Eagles
“Sexy Sadie” – The Beatles (about Maharishi Maresh Yogi)
“American Pie” – Don McLean. (Surely, there’s real person in there somewhere. ;))
"Killing me Softly with His Song – Roberta Flack (about Don McLean)
“Mrs. Robinson” – Simon and Garfunkel ("Where have you gone . . . ")
“Sub Rosa Subway” – Klaatu (about Alfred Beach, who dug the first New York subway)
“Kingfish” – Randy Newman (about Huey Long)
“God Save the Queen” – The Sex Pistols
“Catherine of Aragon,” “Anne of Cleves,” “Catherine Howard,” “Jane Seymour,” “Anne Boleyn” and “Catherine Parr” – Rick Wakeman, on his album The Six Wives of Henry VIII
“Bette Davis Eyes” – Kim Carnes
“Tribute to Robert Johnson” – Delany and Bonnie and Friends (about the blues musician)
“Taxman” – Beatles (mention of the then-leaders of the Conservative and Labour parties)
Adding, Neneh Cherry was a good friend of Lisa Bonet, (when she and Lenny were married) Lenny was cheating on Lisa, Neneh saw him at it and wrote the song as a sort of veiled public diss/jab at Lenny. I think it was a VH1 biography I saw this on, in it he also mentioned that the reason he cut hs dredlocks was as a part of spiritual cleansing/purging to heal from the nasty divorce that eventually ensued.
“Hirricane” by Bob Dylan (Rubin “Hurricane” Carter)
“The Late Great Johnny Ace” by Paul Simon
“Sanz Can’t Dance” by John Fogerty (about a business associate who came to own the CCR catalogue)
Several songs about George HW Bush, including “Keep On Rocking in the Free World,” “Loser” and “Dizz Knee Land”
“If Jesse Don’t Like It” by Loudon Wainrihht III, about Sen. Jesse Helms
Eric Clapton wrote “Beautiful Tonight” about his wife and “Tears In Heaven” about his son.
John Lennon wrote “Oh Yoko,” “Julia,” “Beautiful Boy” and “How Do You Sleep” about his wife, mother, son and Paul