Cliff Potts Cliff Potts is the actor who played the role of Admiral Kennelly in the fifth season episode in . He filmed his scenes on Thursday and Friday on Paramount Stage 8 and Paramount Stage 16 . Potts is perhaps best known for his role as John Keenan in the cult 1972 science fiction film " Silent Running " , directed by Douglas Trumbull . Potts was a recurring performer on the series " The Name of the Game " during its first season ( 1968 - 69 ) and had a role in the acclaimed 1976 mini - series " Once an Eagle " , along with fellow " Star Trek " alumni John Anderson , Darleen Carr , James Cromwell , David Huddleston , George Murdock , Andrew Robinson , William Windom , and Anthony Zerbe . He was also a regular on two short - lived series : 1977 ' s " Big Hawaii " and 1983 ' s " For Love and Honor " . All four of these shows originally aired on NBC . Potts worked with star William Shatner on two occasions . The first was the 1978 made - for - TV movie adaptation of " Little Women " ( also starring John de Lancie , Logan Ramsey , and William Schallert ) . The second occasion was a 1982 episode of " T . J . Hooker " ( co - starring Richard Herd ) . In addition , Potts had a brief recurring role on the hit CBS series " Lou Grant " . One of the three " Lou Grant " episodes in which Potts appeared also featured Parley Baer and Fran Bennett . In 1982 , Potts appeared in two episodes of the short - lived adventure series " Tales of the Gold Monkey " , starring Stephen Collins . In 1988 , Potts had a recurring role as Boaz Harper on the CBS drama " Dallas " , during which time he worked with such " Star Trek " performers as Gerrit Graham , William Smithers ( with whom Potts previously worked with in an episode of " The Bold Ones : The New Doctors " ) , and Beth Toussaint . Potts has also appeared on such television shows as " Owen Marshall : Counselor at Law " ( with Jeff Corey ) , " Ironside " ( with Barbara Anderson and James Gregory ) , " Hec Ramsey " ( with Fionnula Flanagan and Robert Foxworth ) , " Falcon Crest " ( with Robert Foxworth and Nick Ramus ) , " Bret Maverick " ( with Sid Haig ) , " Simon & Simon " ( with John Chandler and Lenore Kasdorf ) , " Alfred Hitchcock Presents " ( with Joseph Ruskin ) , " Starman " ( with John Anderson ) , " Murder , She Wrote " ( with William Windom ) , " Stingray " ( with Walker Edmiston , Samantha Eggar , Robert Harper , and Julianna McCarthy ) , and " MacGyver " ( with Jeff Kober and Nicholas Worth ) . In 1987 , he starred with K Callan in the " CBS Summer Playhouse " presentation , " Day to Day . " Between 1984 and 1987 , Potts made three appearances on the series " Hotel " , each time playing a different character . Among the other " Star Trek " performers he worked with on this program were Miguel Ferrer , Molly Hagan , Barry Jenner , Carlos LaCamara , and Deborah May . More recent TV appearances include episodes of " Baywatch " ( with Todd Bryant ) , " Matlock " ( with David Froman and Gregory Itzin ) , " Civil Wars " ( with Tricia O ' Neil , Richard Riehle , and Don Stark ) , and " Vanishing Son " ( with Steve Rankin ) . In addition to the aforementioned " Silent Running " , Potts ' film credits include the 1968 western " A Man Called Gannon " , the 1971 drama " Sometimes a Great Notion " and the 1972 thriller " The Groundstar Conspiracy " . All three of these movies co - starred DS9 guest actor Michael Sarrazin . " A Man from Gannon " was directed by James Goldstone and also starred John Anderson and Susan Oliver ; " Sometimes a Great Notion " co - starred Sam Gilman and Roy Jenson ; and " The Groundstar Conspiracy " features Alan Oppenheimer . In addition , Potts played the title role in the 1972 western drama " Cry For Me , Billy " , starred with Granville Van Dusen in the 1978 drama " Love ' s Dark Ride " , and worked with John Rhys - Davies in the 1983 adventure " Sahara " . Potts retired from acting in 1999 . However , in 2011 he returned for a supporting role in the family western " Wild Hearts " , written , directed , produced and starring .