Diana Ross & Lionel Richie's "Endless Love" crowns our list of the top duets of all time -- and with good reason. It's not only the biggest No. 1 hit for either artist (it spent nine weeks at the top), but also clung to the chart for an amazing 27 weeks -- a lengthy run for a single back in 1981. Richie wrote the music and lyrics for the soundtrack tune from the Brooke Shields movie of the same name, and recruited diva Ross to accompany him on the song. "Endless" almost returned to the Hot 100 perch nearly 13 years later, when Luther Vandross and Mariah Carey's cover stalled at No. 2 on Oct. 1, 1994.