Before he was the champ, Ali released an album called I Am The Greatest!, but his musical influence is best heard in the songs he inspired.
Bowie's "activist" days of 1964 led to Ziggy Stardust.
With the band in danger of being dropped from their label, Alice Cooper drummer Neal Smith co-wrote the song that started their trek from horror show curiosity to the Rock and Roll Hall of Fame.
How well do you know your David Bowie lyrics? Take this quiz to find out.
We've heard of artists putting their hearts into their music, but some take it literally.
The head of Drake's estate shares his insights on the late folk singer's life and music.
Sting wrote "Fields of Gold" after buying a house near a barley field and enjoying the majestic sunsets.
The Ben Folds Five song "Brick" is about a difficult time when Folds' girlfriend got an abortion.
Meghan Trainor wrote "Lips Are Movin" in just eight minutes with her writing partner Kevin Kadish.
"Lady Marmalade" is the only song to hit #1 twice in both the UK and US.
Eddie Vedder often changes the words when he sings "Yellow Ledbetter." The basic story is about a guy whose brother dies in the first Gulf War. Apparently, bad news in the army is given in yellow envelopes.
"Kickstart My Heart" is about all the ways Motley Crue gets their blood flowing without drugs. It was inspired by their bass player Nikki Sixx, who claimed he had to be revived with a shot of adrenaline to the heart after an overdose.