 Gene Roddenberry (qv) originally conceived the Klingons as looking  more alien than they do in the series, but budget restriction  prevented this. When the show moved to the big screen, he was  finally able to make Klingons look more alien. The resulting  continuity break between TOS and the movies and later series was  addressed in  _"Star Trek: Deep Space Nine" (1993) Trials and Tribble