Longtime friend and colleague of Lucille Ball (better known as TV's Lucy), Doris Singleton is fondly remembered as her "I Love Lucy" rival, Caroline Appleby. Singleton appeared 10 times on the iconic sitcom and twice on Ball's follow-up series, "The Lucy Show." She was set to become a series regular on "Here's Lucy" in 1968, but 11th-hour changes saw the series focus more intimately on Lucy's home life. Singleton nevertheless guest-starred as four characters over the six-season run. Outside her life with Lucy, Singleton was the venerable triple threat: she acted in countless TV classics, sang with an orchestra, and danced as a member of the New York City Ballet over the course of her career. Her dulcet tones garnered her radio roles as well. She lent her voice to "My Favorite Husband" in 1948, a progenitor to the televised Lucy shows where she first met and befriended Ball. Elsewhere in TV Land, Singleton appeared on two episodes of the POW comedy "Hogan's Heroes," was in three episodes of the '60s sitcom staple "The Dick Van Dyke Show," and appeared six times as recurring character Margaret Williams in the CBS sitcom "My Three Sons." Singleton scored another prominent recurring role as a good-natured neighbor in the short-lived comedy of manners "Angel."