Ronne Troup (born June 10, 1945 in Bryn Mawr, Pennsylvania, USA) is an American actress and educator whose acting roles include Polly Williams Douglas on the sitcom My Three Sons.
She appeared, uncredited, as a teen party guest in the Bob Hope film "I'll Take Sweden" (1965). In 1966, she made her film debut as part of the all-girl ensemble in Columbia Films' The Trouble with Angels where she is prominent in the graduation scene. In December 1966, she was cast as Sister Bertrille and had begun filming the pilot for The Flying Nun when she was dropped after the studio's first choice Sally Field finally agreed to accept the role.
She then appeared often on popular dramas Emergency! (in which her stepmother and father co-starred), Marcus Welby, M.D., S.W.A.T. and Adam-12. From 1987 to 1990, she portrayed "Barbara" on the CBS show Knots Landing. In more recent years, Troup has appeared in guest roles on Strong Medicine, The West Wing , and Cold Case.