Don Keefer Donald H . " Don " Keefer was an actor from Pennsylvania who appeared on , playing Cromwell in the second season episode . He filmed his scenes on Monday and Tuesday at the Paramount Pictures backlot and Desilu Stage 10 . Keefer was born as Donald Hood Keefer in Highspire , Pennsylvania , USA on 18 August 1916 . He was one of the founding members of the in Manhattan , New York . He was married to actress Catherine McLeod between 1950 and her death in 1997 . The couple had three sons , Don Keefer Jr . , Tom Keefer , and John Keefer . Tom and John Keefer are working as grips in the camera and electrical department of the film and television industry . He made guest appearances in many other television series , including " Gunsmoke " , " Have Gun - Will Travel " , , " My Favorite Martian " ( starring Ray Walston ) , , " The Andy Griffith Show " , " Bonanza " , " Barnaby Jones " ( with Lee Meriwether ) , " Quincy , M . E . " ( with Garry Walberg and Robert Ito ) , " Starsky & Hutch " ( starring David Soul ) , " Alice " ( with Vic Tayback ) , and " Picket Fences " ( with Ray Walston and Roy Brocksmith ) , as well as the pilot movie for " The Incredible Hulk " . He also appeared in the 1972 TV movie " Columbo : The Most Crucial Game " , along with James Gregory , Susan Howard , and Dean Stockwell . His other TV movies include " Who Is the Black Dahlia " ( 1975 , with Ronny Cox , John Fiedler , and Sid Haig ) , " Lannigan ' s Rabbi " ( 1976 , with Andrew Robinson ) , " The Girl in the Empty Grave " ( 1977 , with Jonathan Banks and James Cromwell ) , " The Immigrants " ( 1978 , with Stephen Macht ) , " Samurai " ( 1979 , with Michael Pataki ) , " The Scarlett O ' Hara War " ( 1980 , with Clive Revill and Warren Munson ) , " Amos " ( 1985 , with Ray Walston and James Sloyan ) , and " Lucy & Desi : Before the Laughter " ( 1991 , with Alan Oppenheimer ) . Keefer also had several films to his credit . He had a small role in the highly - acclaimed , - winning 1969 western " Butch Cassidy and the Sundance Kid " , which also featured fellow TOS guest actors Jeff Corey and Ted Cassidy and guest star Kenneth Mars . Prior to this , he and another TOS guest star , Whit Bissell , had uncredited roles in " The Caine Mutiny " , which was released in 1954 and also earned several Academy Award nominations . That same year , Keefer and Bissell co - starred with William Schallert in " Riot in Cell Block 11 " . Keefer and Schallert would go on to appear in 1955 ' s " An Annapolis Story " and 1958 ' s " Torpedo Run " ( with Richard Carlyle ) . In 1966 , Keefer appeared in the war comedy " The Russians Are Coming , the Russians Are Coming . " Also starring in this film were Brian Keith , Andrea Dromm , and Theodore Bikel . ( Michael J . Pollard made an uncredited appearance . ) In 1970 , he co - starred with Gary Lockwood , Paul Winfield , and Graham Jarvis in " R . P . M . " , and the following year , he and his " Assignment : Earth " co - star Robert Lansing appeared in " The Grissom Gang " , which starred Kim Darby and also featured Hal Baylor . In 1973 , he and Kenneth Tobey appeared in the popular film , " Walking Tall " . That same year , he co - starred with in the latter ' s acclaimed science fiction comedy " Sleeper " . Other film credits include " Incident in an Alley " ( 1962 , with Clegg Hoyt ) , " The Young Nurses " ( 1973 , with Dick Miller ) , " Ace Eli and Rodger of the Skies " ( 1973 , with Bill Quinn ) , " Candy Stripe Nurses " ( 1974 , with Dick Miller and Bill Erwin ) , " Fire Sale " ( 1977 , with Richard Libertini ) , " The Car " ( 1977 , with John Rubinstein and Ronny Cox ) , " Samurai " ( 1979 , with Michael Pataki , Walt Davis , Johnny Haymer , Bob Minor , Tom Lupo and Gregory J . Barnett ) , " Creepshow " ( 1982 , in the same segment which features Adrienne Barbeau , Fritz Weaver , Robert Harper , the film also starred Jon Lormer ) , and " The Marrying Man " ( 1991 , with Jeremy Roberts ) . His last film appearance was in the 1997 comedy " Liar , Liar " , which also featured Anne Haney and Randy Oglesby . Keefer died of natural causes at his home in Sherman Oaks , California on 7 September 2014 .