(written from a Production point of view)
Her other television credits include appearances on Bewitched, The Man from U.N.C.L.E., Bonanza, Land of the Giants, and Melrose Place. She also had a role in 1971's Columbo: Ransom for a Dead Man, as did fellow TOS guest star Paul Carr.
Yarnall made her feature film debut in the 1963 comedy The Nutty Professor, in which she and DS9 guest actor Henry Gibson played college students. In 1968, she co-starred with fellow TOS guest star Robert Walker, Jr. in the film The Face of Eve. She followed this with roles in the Elvis Presley film Live a Little, Love a Little in 1968 and the Academy Award-nominated comedy Bob & Carol & Ted & Alice in 1969.
In 1972, Yarnall had a role in the Charles Bronson action film The Mechanic, as did fellow TOS guest actress Jill Ireland and DS9 guest actor Steve Vinovich. And in 1973, she co-starred with fellow Star Trek actors John Colicos, Joanne Linville, James B. Sikking, and William Smithers in the film Scorpio. More recent film credits include 1987's Fatal Beauty (starring Whoopi Goldberg, Harris Yulin, and Brad Dourif), 1990's Funny About Love (with Michael Bofshever and directed by Leonard Nimoy), and 1993's Born Yesterday (with Michael Ensign and Matthew Faison).
Among her other distinctions, Yarnall was also the last woman to be elected as an original "Miss Rheingold," in 1964. 
In 2009, Yarnall guest voiced the role of T'Pauk on the fan-produced series Star Trek: The Continuing Mission.