John Colicos John Colicos was a Canadian actor who played Kor , the first major Klingon seen on " Star Trek " . As such , Colicos defined the look of the Klingons – mustachioed menaces in the Genghis Khan mold . Originating the role in the first season episode , Colicos was to return as Kor in both and , but scheduling conflicts made this impossible . Regardless , he would be able to reprise the role of Kor several more times on . Colicos filmed his scenes for " Errand of Mercy " on Tuesday at Desilu Stage 9 , Wednesday and Thursday at Stage 10 . In a career that spanned over five decades , Colicos performed in nearly 100 film and television projects . His appearance as Kor in the " Deep Space Nine " episode in was among his last acting roles . Less than two years afterward , Colicos died in his hometown of Toronto , Ontario , Canada , following a series of heart attacks . He was 71 years old . Acting career . Outside of " Star Trek " , Colicos is well - known for his role in another popular science fiction series , . Fans of this series remember Colicos as the traitorous Count Baltar , who sold out humanity to the evil Cylons . Soap opera fans from the eighties may recall him as Mikkos Cassadine with wife Helena portrayed by Constance Towers , a madman bent on destroying s Port Charles . He was also among the regulars of the earlier soap opera " The Secret Storm " . Others who have starred in this latter show include fellow " Trek " alumni as Bibi Besch , Cliff DeYoung , Laurence Luckinbill , and Diana Muldaur . Colicos has many other television appearances to his credit . In 1957 , he appeared with fellow TOS guest star David Opatoshu in an episode of " Studio One " , and in 1962 , he co - starred with fellow future Klingon portrayer Christopher Plummer ( General Chang in ) in the " Hallmark Hall of Fame " production of " Cyrano De Bergerac " . ( He would co - star with Plummer again in the 1988 film " Shadow Dancing " . ) Colicos and Plummer are only a few of the many " Star Trek " actors with training and experience at Canada ' s Stratford Festival ; William Shatner is also among them . These early appearances were followed by three guest spots on , including one episode which also guest - starred Michael Forest , Felix Locher and Judy Levitt ( 1967 ) and another guest - starring Ed McCready , John McLiam , Jason Wingreen , and Charles Napier ( 1968 ) . The third , in 1970 , occurred when his TOS co - star Leonard Nimoy was a regular on the series . That same year , he and Morgan Woodward guest - starred in an episode of " The High Chaparral " , a series starring Henry Darrow . Colicos also guest - starred with Phillip Pine in an episode of " Then Came Bronson " and with Keye Luke and Kenneth Tobey on " It Takes a Thief " . He later guest - starred in a 1972 episode of " The F . B . I . " with Barbara Babcock . In 1975 , he appeared in an episode of " Hawaii Five - O " with George Takei , an episode of " Petrocelli " starring Susan Howard and David Huddleston , and a production of " Harry O " with Henry Darrow , Sabrina Scharf , and Anthony Zerbe . Colicos ' later TV guest appearances include " Charlie ' s Angels " ( with Perry Lopez ) , " Vega $ " ( with Stephen Brooks and Alex Henteloff ) , " Scarecrow and Mrs . King " ( with Kenneth Tigar ) , " Beyond Reality " ( starring Nicole de Boer ) , and " Fast Track " ( with Duncan Regehr ) . He even briefly ventured into voice acting , playing the evil Apocalypse in the animated " X - Men " series ( which also featured the voice of Iona Morris as Storm ) . Colicos starred in the role of Porthos in the 1960 TV movie adaptation of " The Three Musketeers " , co - starring Mark Lenard . Other TV movie credits include " Goodbye , Raggedy Ann " ( 1971 ) with Walter Koenig , " Portrait : A Man Whose Name Was John " ( 1973 ) with David Opatoshu and Henry Darrow , and " A Matter of Wife . . . and Death " ( 1976 ) with Marc Alaimo . He also appeared in the 1978 mini - series " The Bastard " with Ian Abercrombie , Kim Cattrall , John de Lancie , James Gregory , Alex Henteloff , and " Errand of Mercy " co - star William Shatner and in the 1997 mini - series " The Last Don " with Kirstie Alley , Seymour Cassel , Joseph Ruskin , and Mike Starr . Colicos had been extremely active in film , as well . Among his most notable works in this medium were " Anne of the Thousand Days " ( 1969 , with Geneviève Bujold and Whit Bissell ) , " Doctors ' Wives " ( 1971 , with Jon Lormer ) , " Red Sky at Morning " ( 1971 , with Kim Darby , Nehemiah Persoff and Gregory Sierra ) , " The Wrath of God " ( 1972 , co - starring Frank Langella and Gregory Sierra ) , " Scorpio " ( 1973 , with Joanne Linville , James B . Sikking , William Smithers , and Celeste Yarnall ) , and " The Postman Always Rings Twice " ( 1981 ) . He had his largest film role in the latter , which also featured an appearance by fellow Klingon portrayer Christopher Lloyd ( Kruge in ) . Colicos made his final acting appearance in the concept demonstration trailer for " Battlestar Galactica : The Second Coming " , in which he reprised his role as Count Baltar for the first time in nearly twenty years . The four - minute trailer , which premiered at DragonCon in Atlanta , Georgia , in July 1999 , was actually part of a thirty - minute pilot film for a proposed new " Battlestar Galactica " television series that would have continued where the original series left off . Also starring in the film were fellow " Star Trek " performers Richard Lynch and George Murdock . However , the project was never picked up , and the entire pilot film has never been shown publicly . Colicos died less than a year after the trailer was first screened .