Langdon Elwyn Mitchell (February 17, 1862 – October 21, 1935) was an American playwright who was popular on Broadway during the early twentieth century.

A member of the American Academy of Arts and Letters, he wrote plays under his own name and poetry under the pen name "John Philip Varley."

Along with Clyde Fitch, William Vaughn Moody, Percy MacKaye, Ned Sheldon and Rachel Crothers, Langdon Mitchell was regarded as one of the more serious American dramatists in an era (c. 1900-1910) not notable for weighty plays.

Mrs. Fiske acted one of her most lauded roles, the conniving Becky Sharp, in 1899 in Mitchell's dramatization of Thackeray's Vanity Fair, and she starred seven years later in his most famous work, The New York Idea, a play which had been written for her.

It was revived off-Broadway in New York in 1977, in a production starring Blythe Danner, and again in 2011, in an adaptation by David Auburn, the author of Proof.)