Mercer Kennedy Ellington (11 March 1919 – 8 February 1996) was an American jazz trumpeter, composer, and arranger.
Ellington was born in Washington, DC, the son of the composer, pianist, and bandleader Duke Ellington and Edna Thompson. By the age of eighteen he had written his first piece to be recorded by his father ("Pigeons and Peppers").
In 1939, 1946–1949, and 1959 he led his own bands, many of whose members went on to play with his father, or to achieve independent fame (notably Dizzy Gillespie, Kenny Dorham, Idrees Sulieman, Chico Hamilton, Charles Mingus, and Carmen McRae). During the 1940s in particular he wrote pieces that became standards, including "Things Ain't What They Used to Be", "Jumpin' Punkins", "Moon Mist", and "Blue Serge". He also wrote the lyrics to Hillis Walters' popular song, "Pass Me By" (1946), which was recorded by Lena Horne, Carmen McRae and Peggy Lee.
He composed for his father from 1940 to 1941, worked as road manager for Cootie Williams' orchestra (1941 to 1943 and again in 1954), and returned to work for his father playing E-flat horn in 1950, and then as general manager and copyist from 1955 to 1959. In 1960 he became Della Reese's musical director, then in 1962 went on take a job as a radio DJ in New York for three years. In 1965 he again returned to his father's orchestra, this time as trumpeter and road manager.