Authors Born on December 21
- A. J. Bowen Actor, 1977
- Adam Schefter Writer, 1966
- Albert Lee Guitarist, 1943
- Albert Payson Terhune Author, 1872
- Alicia Alonso Ballet Dancer, 1921
- Amy Butler Greenfield Designer, 1968
- Andy Dick Actor, 1965
- Andy Van Slyke Baseball Player, 1960
- Anthony Powell Novelist, 1905
- Arnold Friberg Illustrator, 1913
- Barbara Fialho Model, 1987
- Barbara Roberts Politician, 1936
- Benjamin Disraeli Politician, 1804
- Betty Wright Singer, 1953
- Bhavin Turakhia Businessman, 1979
- Brad Tavares Mixed Martial Artist, 1987
- Carl Wilson Musician, 1946
- Charles Michel Minister, 1975
- Chris Evert Tennis Player, 1954
- Clara Lucas Balfour Author, 1808
- DaBaby Rapper, 1991
- Dame Cicily Isabel Fairfield DBE Author, 1892
- David Baker Composer, 1931
- David Hillis Biologist, 1958
- Donald T. Regan Statesman, 1918
- Edward Hoagland Author, 1932
- Elisabeth Elliot Author, 1926
- Emmanuel Macron Politician, 1977
- Eric Johnston Businessman, 1896
- Ernst Grunfeld Chemist, 1893
- Florence Griffith Joyner Sprinter, 1959
- Frank Zappa Musician, 1940
- George Ball Diplomat, 1909
- Ha Ha Clinton-Dix American Football Player, 1992
- Jack Nance Actor, 1943
- James Lane Allen Novelist, 1849
- Jane Fonda Actress, 1937
- Jane Kaczmarek Actress, 1955
- Jeffrey Katzenberg Businessman, 1950
- Jillian Mayer Artist, 1986