Theresa Helburn (January 12, 1887 – August 18, 1959) was an important figure in 20th-century American theater and a Bryn Mawr College alumna, best known for her work with New York's Theatre Guild. Involved with The Theatre Guild from its foundation in 1919, Helburn served first as a literary manager and then as casting director and eventually became (along with Lawrence Langner) a co-producer. The Theatre Guild specialized in bringing the highest-quality drama of Europe and America to Broadway stages. Breaking away from the common practice of single-ticket sales and productions built around famous stars, the Theatre Guild built a large and loyal season subscription audience as well as establishing enduring relationships with renowned playwrights such as George Bernard Shaw and Eugene O'Neill, as well as the actors Alfred Lunt and Lynn Fontanne, among many other notable names. She and the other founding members of this production company brought serious, ground-breaking plays back to the Broadway stage, and together they proved that it was possible to produce work that was both artistically and commercially successful.