Among his many television appearances, one of his more well-known roles is that of Esteban Rodriguez in the classic Star Trek episode "Shore Leave". Lopez also appeared in an episode of Bonanza, as the cold-blooded outlaw Duke Miller, who kills a man over being first in line to get a haircut. He was Joaquín Castañeda, a mestizo that fought to free his people, on Zorro, starring Guy Williams. Lopez also appeared in episode 14, "Night Of The Long Knives" originally airing December 16, 1966 of The Time Tunnel television series; the Voyage to the Bottom of the Sea episode "Savage Jungle"; McLintock! (1963) as Davey Elk; the Juan Moreno's Body as a migrant Mexican fruit picker accused of murdering the son of the owner of the orchard; and Kelly's Heroes (1970) as Pvt. Petuko.