Her niche as a minor actress
Mary Treen, Cousin Tilly in It's a Wonderful Life
Mary Treen (March 27, 1907 – July 20, 1989).
Mary Treen (born Mary Louise Summers) was an American film and television actress. A minor actress for much of her career, she managed to secure a plain, unassuming niche for herself in the Hollywood of the 1940s, 1950s, and 1960s.
Treen appears in the movie It’s a Wonderful Life as Cousin Tilly. She also guests in three episodes of The Donna Reed Show in “The Beaded Bag” (Season 1, Episode 12); “Weekend” (Season 3, Episode 1); and “Do Me a Favor – Don’t Do Me Any Favors” (Season 8, Episode 7).