Check out Billboard's picks for Willis' 10 most influential songs below.
10. "The D" (2018)
Willis spent the better part of six years putting together a multi-media love letter to her hometown, anchored by this ebullient song that layered performances from 5,000 singers and instrumentalists, including the MC5's Wayne Kramer, Motown luminaries Martha Reeves, Lamont Dozier, Valerie Simpson and Paul Riser, actress Lily Tomlin, Mayer Hawthorne and Grammy Award-winning producer Narada Michael Walden.
9. "Ain't No Man Worth It" (1974)
Childstar, Willis' sole album as a solo artist, may have been a commercial dud but had its moments -- most notably this soulful, pensive, piano-led track about lessons well learned, with an arrangement that nodded to Carole King and Laura Nyro's collaboration with Labelle.
8."You're the Best," Joe Esposito (1984)
Willis teamed with Bill Conti for this power ballad theme song from The Karate Kid -- finding a home after being originally written for Rocky III (replaced by Survivor's "Eye of the Tiger") and then pitched for Flashdance, which went for Michael Sembello's "Maniac" instead. It's also been used by South Park, The Simpsons, Bob's Burgers and more.
7. "I'm Here," The Color Purple: A New Musical (2005)
Willis, Brenda Russell and Stephen Bray scored deserved Tony Award nominations and a Grammy win for their work on the stage adaptation of Alice Walker's novel and Steven Spielberg's film. There's plenty of strong material throughout, but main character Celie's empowerment declaration is the money shot, a soulful and soul-rending release from decades of abuse and servitude that stands capably outside of the rest of the musical.
6. "Boogie Wonderland," Earth, Wind & Fire featuring the Emotions (1979)
Willis paired with Jon Lind to create this Grammy-nominated disco classic from EWF's I Am album, for which she co-wrote seven of nine tracks.
5. "Neutron Dance," The Pointer Sisters (1984)
Written by Danny Sembello originally for the Streets of Fire soundtrack, this jittery dance track -- lamenting that there's "no time to stop and get away/because I work so hard to make it every day" -- wound up in Beverly Hills Cop and winning a Grammy as part of its companion album. The Top 10 smash was also the caboose for the Pointers' mid-'80s renaissance that also included "Automatic," "Jump (For My Love)" and "I’m So Excited."
4. "In the Stone," Earth, Wind & Fire (1979)
Though not Willis' biggest hit for EWF, the brassy "In the Stone" -- co-written with Maurice White and David Foster -- was a blast-off for the I Am album and for many an EWF concert since. It also popped up 23 years later in Drumline.
3. "What Have I Done to Deserve This?," Pet Shop Boys featuring Dusty Springfield (1987)
Willis hooked up with Neil Tennant and Chris Lowe via a mutual friend in the publishing industry, writing this single about three years before its release, with the duo using the interim to refine the song's structure and get Springfield on board. Clearly well worth the wait, and the effort.
2. "I'll Be There For You," The Rembrandts (1994)
Willis was part of a team of six, including the Rembrandts' Danny Wilde, who created this iconic theme for NBC's Friends, which the band turned into a full-scale song after a Nashville radio station famously looped the TV version into a single-length hit.
1. "September," Earth, Wind & Fire (1978)
Willis' first co-wrote for EWF -- with the group's Maurice White and Al McKay -- was also the best song of her career, a joyful three and a half minute party that gets you on your feet from the first skittering guitar notes.
While writing, she was not a fan of White's "ba-dee-ya" lyrics and fought to fill those in with real words; subsequently she called it "the greatest lesson I ever had in songwriting -- a great groove can make any lyric work." We knew love, and this song, were here to stay.