Robert Viharo (born August 14, 1942) is an American actor. He made an early appearance in 1966 as Harry in Dark Shadows. He is known for his role in Valley of the Dolls (1967) in the part of a Broadway director. He had the starring role as Zachary Kane in the action film Bare Knuckles (1977). He also played the part of Col. Ernesto Dorio in the film Romero (1989).

From 1966 to 1991, he appeared in numerous television shows. In Dark Shadows in 1966, he played the part of Harry. In the same year, he was in The Fugitive. In the Gunsmoke episode "The Sodbusters" (1972), he played the part of the gunslinger Dick Shaw. In The High Chaparral episode "Alliance" (1969), he played the part of Johhny Ringo.