Mary Martha Byrne is an American actress, singer and television writer. She played the role of Lily Walsh Snyder on the soap opera As the World Turns from 1985 to 1989, then again from 1993 to 2008; as well as, from 2000 to 2003, Lily's twin sister, Rose D'Angelo. Byrne has also appeared in other stage, television and movie roles, including the title role in the 1983 film Anna to the Infinite Power. She is currently executive producer of the digital drama series Anacostia, where she has played the role of Alexis Jordan since 2011. Byrne has won three Daytime Emmy Awards for acting.

As the World Turns is an American television soap opera that aired on CBS for 54 years from April 2, 1956, to September 17, 2010. Irna Phillips created As the World Turns as a sister show to her other soap opera Guiding Light. With 13,763 hours of cumulative narrative, As the World Turns has the longest total running time of any television show. In terms of continuous run of production, As the World Turns at 54 years holds the fourth-longest run of any daytime network soap opera on American television, surpassed only by General Hospital, Guiding Light, and Days of Our Lives. As the World Turns was produced for its first 43 years in Manhattan and in Brooklyn from 2000 until 2010.