Arthur Russell Thorndike (6 February 1885 – 7 November 1972) was a British actor and novelist, best known for the Doctor Syn of Romney Marsh novels.

Less well-known than his sister Sybil but equally versatile, Russell Thorndike's first love was writing and, after serving in World War I, he devoted himself to it.

They became students at Ben Greet's Academy and two years later accompanied fellow members of the company on a North American tour, which included New York City.

He ended his film career in minor priest roles for Laurence Olivier in Hamlet (1948) and Richard III (1955).

Thorndike and his wife had five children: Daniel (1920-2016), an actor; Dickon (1921-2016); Jill (1924-2013); Georgia (born 1927), who married the theatre administrator David Peacock; and Rhona (1929-2016).