Starting off in the 1970s, Colen landed roles early in her career in both film and television. During the early seasons of Happy Days, she starred as Milwaukee-based carhop Marsha Simms in seasons 1-3 and 5.
She was the first Actress to portray Etta Candy in the live action adaptation of the DC comic book series Wonder Woman. After the pilot, she only appeared during the series' first season (1976–77), which were set during World War II. When the series was retooled and reset in modern times, the character was dropped.
Colen was married to Patrick Cronin on October 23, 1977 and together they had two sons, James Cronin and Charlie Cronin. She died of lung cancer on November 18, 1999 in Los Angeles, California, at the Cedars-Sinai Medical Center. Colen died on the opening night of Brentwood High School's production of The Man Who Came to Dinner, which was written by her grandfather, Pulitzer Prize-winning Playwright George S. Kaufman, and which starred her son, James Cronin, in the title role of Sheridan Whiteside. Her memorial Service was held at Saint James Episcopal Church in Los Angeles ten days later.
Colen acted in such television film as Schoolboy Father (1980), Brave New World, and in feature films such as Lifeguard, High Anxiety, American Pop, and Who's that Girl?.
She also guest starred on a number of TV shows such as The Odd Couple, All in the Family, The Love Boat, Barney Miller (1981, episode: "The Rainmaker"), The Wonder Years, and Baywatch.
Her final television appearance before retiring was in a 1997 episode of Nickelodeon's The Secret World of Alex Mack.
