Dark and his wife, Eleanor, were married from 1948 until his death. The couple had one child.
In 1954, Dark played in an episode of the TV series, The Lone Ranger, entitled Texas Draw. In 1955, Dark was cast in an episode of the NBC western anthology series, Frontier, hosted by Walter Coy. Dark guest starred on two episodes of the ABC religion anthology series, Crossroads, as Irving Green in "The Unholy Trio (1955) and as Frank Corletto in "Circus Priest" (1956).
In 1956, Dark appeared in two episodes of Science Fiction Theatre, S2E6 "Bullet Proof," and S2E9 "End of Tomorrow."
In 1957 and 1958, Dark guest starred in two episodes of David Janssen's crime drama, Richard Diamond, Private Detective, as the lead in "The Mickey Farmer Case" and then as Rudi Trekhala in "Widow's Walk". About this time, he also guest starred on John Bromfield's crime drama, U.S. Marshal. In 1957, he played Sgt. Al Zavala in four episodes of the syndicated crime drama, Code 3, with Richard Travis in the lead role of assistant Sheriff Rodger Barnett.
In 1958, Dark appeared as Don Ramon in "Decoy" on the ABC/Warner Brothers western series, Colt .45, starring Wayde Preston. That same year, Dark played the main villain, william Swanson, in the episode "The Young Gun" in Robert Culp's western series, Trackdown.
Dark appeared in 1959 as Juan Carlos Morita in the episode "Death of a Gunfighter" on CBS' "Have Gun Will Travel" and as Trevor Jackson in the episode "Reunion" of CBS's The Texan, starring Rory Calhoun; his fellow co-stars were Bethel Leslie and Robert F. Simon.
In 1960, he was cast as Miguel Avarado in the episode "Bandido" of the syndicated western series, Pony Express, starring Grant Sullivan. His fellow guest stars in the segment were Douglas Kennedy and Robert Ivers.
Dark played the role of Pike in the three-part 1964 episode, "The Tenderfoot", of NBC's Disney's The Wonderful World of Color.