Although Father Mulcahy was originally conceived as a semi-regular role on Twentieth Television's hit series M*A*S*H, William Christopher's captivating performances soon made the spiritual advisor of the 4077th a regular fixture.

Following M*A*S*H, Christopher co-starred with fellow M*A*S*H alums Harry Morgan and Jamie Farr in AfterMASH, which looked at the characters' return to civilian life.

After graduating from New Trier High School in Winnetka, Illinois, Christopher attended Wesleyan University in Middletown, Conneticut. He majored in drama and was active in fencing, soccer, singing with the glee club and performing in various dramatic productions. During his school days, Christopher met his future wife on a blind date. Christopher and the former Barbara O'Connor are still happily married and are the parents of two sons, John and Ned.

After appearing in a variety of regional productions, Christopher landed roles in a number of off-Broadway productions, most notably The Hostage at One Sheridan Square. His Broadway debut came in Beyond the Fringe, a British revue.

Christopher left the New York stage for Hollywood television production, where he was seen in The Andy Griffith Show, Death Valley Days, The Patti Duke Show and The Men from Shiloh. Christopher had recurring roles on Gomer Pyle, USMC, That Girl and Hogan's Heroes. Since M*A*S*H, Christopher has appeared on various series, including Murder, She Wrote.

In feature films, Christopher performed in The Fortune Cookie, The Private Navy of Sgt. O'Farrell, The Shakiest Gun in the West, With Six You Get Egg Roll and Hearts of the West. He won parts in such telefilms as The Movie Maker, The Perils of Pauline and For the Love of It.

Christopher devotes much of his spare time to the National Autistic Society because his son Ned is autistic. He has done public service announcements to bring attention to this serious problem. In 1985 he and his wife wrote Mixed Blessings, a book about their experiences raising their Ned.