Charles Tate Regan, Fellow of the Royal Society (1 February 1878 – 12 January 1943) was a British ichthyologist, working mainly around the beginning of the 20th century. He did extensive work on fish classification schemes.
Born in Sherborne, Dorset, he was educated at Derby School and Queens' College, Cambridge and in 1901 joined the staff of the Natural History Museum, where he became Keeper of Zoology, and later director of the entire museum, in which role he served from 1927 to 1938.
Regan was elected Fellow of the Royal Society in 1917.
Regan mentored a number of scientists, among them Ethelwynn Trewavas, who continued his work at the British Natural History Museum.