She appeared in a key role as a native medicine woman and femme fatale in one of the original Star Trek episodes, "A Private Little War" (1968).

[8] As her profile increased, Kovack began to gain roles in Hollywood movies, most notably as the high priestess Medea in Jason and the Argonauts (1963).

She also had roles in Strangers When We Meet (1960) with Kirk Douglas and Kim Novak, Diary of a Madman (1963) with Vincent Price, The Outlaws Is Coming (1965) with The Three Stooges, Sylvia (1965) with Carroll Baker, The Great Sioux Massacre (1965), The Silencers (1966) with Dean Martin, Tarzan and the Valley of Gold (1966) with Mike Henry, Frankie and Johnny (1966) with Elvis Presley, and Carl Reiner's directorial debut, Enter Laughing (1967).

Credited as Nancy Mehta, she played the murder victim in the TV movie/series pilot Ellery Queen (also known as Too Many Suspects, 1975).

[citation needed] Kovack spent two-and-a-half years in Iran, and starred in three films that were made there, returning to the United States in 1968.