James Cox (July 28, 1882 – March 3, 1925) was an American vaudeville performer and songwriter famous for his Roaring Twenties hit "Nobody Knows You When You're Down and Out", written in 1923.
Bessie Smith made the song famous and it was later repopularized by Derek and the Dominos (featuring Eric Clapton and Duane Allman) on the album Layla and Other Assorted Love Songs. It was reintroduced to a fresh generation of music fans when Clapton performed the song in his 1992 MTV Unplugged appearance, which was also released on the album Unplugged. The song has been covered by a wide variety of artists, including Louis Jordan, Scrapper Blackwell, Peter, Paul and Mary, The Chad Mitchell Trio, Dave Van Ronk, Otis Redding, Popa Chubby, The Allman Brothers Band, Rod Stewart, Janis Joplin, B.B. King, Nina Simone, Sam Cooke, Bobby Womack, Katie Melua, Dutch Tilders, Steve Winwood with The Spencer Davis Group, Emmy Rossum, Leslie Odom Jr., Jorma Kaukonen and La Santa Cecilia.
Jimmy Cox's daughter, Gertrude "Baby" Cox, sang with Duke Ellington's orchestra in 1928.