Thereafter, McGrath was a guest star on two network westerns, as stagecoach driver Neddie Henshaw on the 1966 episode "Linda" of NBC's "The Virginian" and as Buster in the 1967 episode "Plunder at Hawk's Grove", of ABC's "The Big Valley". Shortly before his death, McGrath played a bartender in the picture "The War Wagon", the character Ned Martin in "Gunfight in Abilene", and Ballard Weeks in Glenn Ford's,"The Last Challenge". All three films were released in 1967. His last role was as Mr. Remington in the Don Knotts comedy-western, "The Shakiest Gun in the West", released in 1968, the year after McGrath's passing. His former "Wagon Train" costar Terry Wilson also appears with McGrath in "The War Wagon" and "The Shakiest Gun in the West." McGrath died at the age of sixty-four of a heart attack in Beverly Hills, California. He is interred at Forest Lawn Memorial Park in Glendale, California. His widow, the former Libby Quay Buschlen (1902-1978), a native of Ontario, Canada, was the daughter of George and Caroline Andrews Buschlen. Libby McGrath outlived her second husband by eleven years. She had a son, Quay Casey Dillon (1924-2006), from her marriage to George Vernon Cassey (1896-1949), a native of Kansas who served in World War I and is interred at the Los Angeles National Cemetery. Libby McGrath is interred by neither husband but at Valhalla Memorial Park Cemetery in North Hollywood, California. McGrath was the second cast member of "Wagon Train" to die. Ward Bond died early in November 1960. Other "Wagon Train" co-stars who have since died are Terry Wilson, John McIntire, Robert Horton, and Denny Scott Miller. Still living are former "Wagon Train" co-stars Robert Fuller and Michael Burns. In the fall of 1968, CBS resurrected McGrath's Charlie Wooster character for the western series, "Lancer", starring Andrew Duggan as a ranch owner. The Wooster-style role was taken by Paul Brinegar, formerly the Wishbone character on "Rawhide", who then played a cantankerous cook named Jelly Hoskins.