2. Ricardo Montalban
Arguably one of the most intense villains in film history, Khan was every bit the epitome of revenge. He first appeared in the Original Series episode "Space Seed" and it's no surprise that the producers of Star Trek II: The Wrath of Khan brought back the original actor to reprise the role. Montalban delivered a skilled performance in Space Seed as the former dictator, cast out by those he lorded over hundreds of years ago. At the time, it was simply a case of him trying to find a way to resurrect his throne. Smooth and slick, this youthful Khan was created by Montalban's performance, as the baddie you loved to hate. However, his performance in "Space Seed" was eclipsed when he returned in Wrath of Khan with the primary purpose of avenging his second bout in exile, at the hands of the now 'Admiral' Kirk. Every breath Ricardo takes, every inflection, each cold calculating look in his eyes cries vengeance and hatred for the man he sees as responsible for the death of his wife. Credit must also go to the writers who give Ricardo some beautifully poetic dialogue to help create this image of a highly intellectual and yet twisted and deranged madman. Heavy lies the crown for Montalban but he wears it well. He oozes confidence and sophistication with his stature and his determination. To the very bitter end, he had us captivated and wanting more. A very close 2nd in my list of the top 5 best guest stars of Star Trek.