"Mood Indigo", "It Donít Mean A Thing If It Ainít Got That Swing":   both songs were composed by Duke Ellington.   The Duke wasnít just the greatest Jazz performer of all times, he was the greatest Jazz composer of all times.
Back in the early days of Jazz, there were "legitimate" composers (Arnold Schoenburg, Anton Webern) and there were "Jazz" composers (Fats Waller, Louis Armstrong).   Then along came George Gershwinís Porgy and Bess , and Igor Stravinsky tried his hand at writing Jazz.   Now Twentieth Century composers are all just Music composers, and Duke Ellington is among the giants of the Twentieth Century.