Otto James "Toby" Hardwicke (May 31, 1904 – August 5, 1970) was an American saxophone player closely associated with Duke Ellington. Hardwick began his musical career on the string bass at age 14, later transitioning to the C melody saxophone before settling on the alto saxophone. A childhood friend of Duke Ellington, he joined Ellington's first band in Washington, D.C., in 1919. Hardwick also performed for banjoist Elmer Snowden at Murray's Casino.

In 1923, Hardwick, Ellington, Snowden, trumpeter Arthur Whetsel, and drummer Sonny Greer found success as the Washingtonians in New York City. Following a financial dispute, Snowden left the band, and Ellington took over as leader. The band played at the Kentucky Club in Times Square for three years, where they connected with Irving Mills, who produced and published Ellington's music.

Throughout the 1920s, Hardwick occasionally played violin and string bass but specialized in alto saxophone, also performing on clarinet and various saxophones. He left Ellington's band in 1928 to tour Europe, collaborating with Noble Sissle, Sidney Bechet, and Nekka Shaw's Orchestra, and led his own orchestra before returning to New York in 1929. After a brief stint with Chick Webb, he led his own band at the Hot Feet Club in 1930, with Fats Waller on the rhythm section, and later at Small's.

Hardwick rejoined Ellington in 1932, playing lead alto saxophone until 1946. Although rarely featured as a soloist, his creamy tone was a staple in the Ellington reed section, except when Johnny Hodges' sharper tone was preferred. Notable exceptions where Hardwick was featured include "Black and Tan Fantasy," "In a Sentimental Mood," and "Sophisticated Lady." He left the band in 1946 due to Ellington's disapproval of his girlfriend and briefly freelanced before retiring from music.

James Lincoln Collier's biography of Ellington credits Hardwick with contributing melodies to "In a Sentimental Mood," "Sophisticated Lady," and "Prelude to a Kiss."