 Mexican actor Ricardo Montalbán was cast as the genetic superman Khan Noonian Singh , having been the first choice for the role . He had been suggested by casting director Joseph D 'Agosta , who was not looking to cast an actor of a particular ethnic background due to Roddenberry 's vision for the series ; Roddenberry wanted to show his perceived 23rd century values by not requiring any specific ethnicities when casting actors in guest roles . Montalbán had previously appeared in a television movie created by Roddenberry , The Secret Weapon of 117 ( also referred to as The Secret Defense of 117 ) , which was the writer 's first attempt to create science fiction on television and aired more than ten years before Star Trek . Montalbán called his role as Khan " wonderful " , saying that " it was well @-@ written , it had an interesting concept and I was delighted it was offered to me " . The main cast were enthusiastic about working with Montalbán ; DeForest Kelley later said " I enjoyed working with Ricardo the best . I was privileged . He is a marvelous actor . " 
