Adele Astaire (September 10, 1897 -January 25, 1981) was an American dancer and entertainer. She was Fred Astaire's elder sister.

She was born Adele Marie Austerlitz in Omaha, Nebraska to Frederick Austerlitz (- 1924), a Vienna-born brewer, and his wife, Ann Gelius (-1975).

When she was five years old she had a successful vaudeville act with her younger brother Fred Astaire that developed into a celebrated adult stage career on Broadway. She was, in fact, the bigger star of the two during their time performing together.

On May 9, 1932, she retired from the stage to marry Lord Charles Arthur Francis Cavendish (August 29, 1905 - March 23, 1944), the second son of the 9th Duke of Devonshire, and moved to Ireland, where they lived at Lismore Castle. She had three children, a daughter (in 1933) and twin sons (in 1935), all of whom died soon after birth. Adele Cavendish married, on April 20, 1947, as her second husband, Col. Kingman Douglass, an American investment banker and Air Force officer who was an assistant director of the Central Intelligence Agency; he died in 1971.

She is said to have had a lesbian relationship with Mercedes de Acosta and was known for her delightfully ribald personality. According to the memoirs of Richard McKenzie (husband of Fred's daughter, Ava), Adele, aka Dellie, was playing Scrabble with her brother when he noticed that she had started a word with the letters C-U-N. He protested at what appeared to be an emerging vulgarity, though Adele later told Ava, "I could have been spelling anything! Like cunnilingus."

She died in Tucson, Arizona.