Susan Howard Jeri Lynn Mooney , better known as Susan Howard , is the American actress who played Mara , the first female Klingon to appear in " Star Trek " , and one of only two ( and the only one with a speaking part ) ever seen in , in the episode . She filmed her scenes between Friday and Thursday at Desilu Stage 9 . Howard was born in Marshall , Texas , and graduated from Marshall High School in the early 1960s . She attended the University of Texas for two years , after which she moved to California , becoming a member of the Los Angeles Repertory Company . She began acting on television programs in 1966 . Outside of " Star Trek " , Howard is best known for playing Donna Culver Krebbs on the primetime soap opera from 1979 through 1987 . This role actually began with a single guest appearance in 1979 , but the producers liked her performance so much that they asked her to return , and she played the character for an additional eight years . Throughout her run on this series , she co - starred with other " Trek " actors , including Barbara Babcock , Joanna Cassidy , Glenn Corbett , Barry Jenner , Leigh J . McCloskey , Derek McGrath , Bert Remsen , William Smithers , Paul Sorenson , Ray Wise , and Morgan Woodward . Howard also tried her hand at writing for the series , ultimately becoming a member of the Writers Guild of America , a position which she still holds . Prior to " Dallas " , Howard was a regular on the legal drama series " Petrocelli " ( 1974 - 76 ) , playing lawyer Tony Petrocelli ' s wife ( a role played by Diana Muldaur in the 1970 movie " The Lawyer " , from which the " Petrocelli " series was spun off ) . David Huddleston was also a regular on this series ; the show ' s pilot movie , entitled " Night Games " , co - starred Henry Darrow . Other guest appearances on the show include William Shatner , John Colicos , Susan Oliver and Glenn Corbett among others . Howard ' s performance on " Petrocelli " garnered her nominations from both the s and the s . Despite this , the series was canceled in 1976 . In addition , Howard has made guest appearances on such TV series as " I Dream of Jeannie " ( working with Lou Antonio and Ted Cassidy ) , " The Flying Nun " ( including an episode with Michael Pataki ) , " Bonanza " ( with John Beck , Dean Stockwell , and Harry Townes ) , and " Mission : Impossible " ( co - starring James B . Sikking and Paul Sorensen and directed by Reza Badiyi ) . Shortly after working with Michael Ansara on " Star Trek " , she appeared with him in an episode of " Here Come the Brides " , a series which starred TOS guest stars Robert Brown , Mark Lenard and David Soul . Howard reunited with her TOS co - star William Shatner in the unsold TV pilot , " Indict and Convict " . Alfred Ryder and Michael Pataki appeared in this project , as well . Howard has also starred in a number of made - for - TV movies , including " The Silent Gun " ( 1969 , with John Beck , Walker Edmiston , and Michael Forest ) , " Columbo : The Most Crucial Game " ( 1972 , with James Gregory , Don Keefer and Dean Stockwell ) , and " Superdome " ( 1978 , with Jane Wyatt and Michael Pataki ) . She has only three feature films to her credit . The first was the 1977 drama " Moonshine County Express " , in which she starred with fellow TOS guest stars Morgan Woodward and Jeff Corey . That same year , she starred in the biker movie " Sidewinder 1 " , which also featured Byron Morrow . Most recently , she co - starred with Stanley Kamel in the 1993 independent drama " Come the Morning " . Other " Trek " connections . Additional television projects on which Howard has worked with other " Star Trek " alumni are as follows :