1960s to 1980s
Donahue played Georgiana Balanger, the niece of George and Martha Wilson, in the episode "Dennis and the Wedding" (1960) on Dennis the Menace. Donahue was also cast, in 1960, with Marion Ross in an episode ("Duet") of The Brothers Brannagan. She played Miriam Welby on ABC's The Odd Couple, Jane Mulligan on Mulligan's Stew, and evil Nurse Hunnicut on Days of Our Lives.
She was part of the main cast for the first season of CBS's The Andy Griffith Show, as Andy's pharmacist love interest Ellie Walker. She was even mentioned in the opening credits before Don Knotts. After one season (1960–1961), Donahue asked for a release from her three-year contract. She and Ron Howard are the last surviving regularly credited cast members from that show.
In 1963, Donahue was cast in an episode of NBC's short-lived modern Western series, Redigo, with Richard Egan as the rancher Jim Redigo. Then she played in another Western series Have Gun Will Travel as Letty May in the episode "The Burning Tree".
In 1964, she appeared in the NBC TV series The Eleventh Hour, a medical drama dealing with psychiatry, starring Jack Ging and Ralph Bellamy, where she played the role of Melanie in the episode "The Secret in the Stone".
In 1966, she guest-starred on the TV series A Man Called Shenandoah, episode 8, "Town On Fire".
In 1967, she guest-appeared on Star Trek in the second-season episode "Metamorphosis" as commissioner Nancy Hedford.
Donahue portrayed the sister of Sister Bertrille (Sally Field) in three episodes of ABC's The Flying Nun (1968–70).
She portrayed Miriam Welby in 17 episodes of The Odd Couple (1972–75).
In 1977, she appeared in an episode of the ABC crime drama The Feather and Father Gang.
In 1978, Donahue starred in the NBC sitcom Please Stand By.
In 1979, she appeared on Diff'rent Strokes as a fiancée to Mr. Drummond in season 1.
In 1981, Donahue appeared in an episode of One Day at a Time, as Alex's mother Felicia.
In 1984, she made an appearance as Mrs. Broderick, the mother of a teenage drug addict on the last season of Happy Days.
In 1987, she played the title character's mother in the short-lived Fox series The New Adventures of Beans Baxter.
In 1988, she appeared in a Newhart episode ("Courtin' Disaster").
In 1989 she appeared in an episode of The Golden Girls as the newest wife of Dorothy Zbornak's ex-husband, Stan.
