10) Fringe (2009-2012)
There were two surprises at the end of the first season finale of Fringe. The big one was when FBI Agent Olivia Dunham found herself atop the still standing World Trade Center in an alternate universe, but the smaller, more meta one, was when Leonard Nimoy stepped out of the shadows as William Bell. The appearance of Bell had been teased since the very beginning of the series. He was an inventor and industrialist that was part Howard Hughes and part Steve Jobs, so it required a special delicacy in casting.
As Bell, Nimoy brought the right mix of paternal caring and enigmatic charisma. Could you trust him? No, probably not. But re-purposing the face and voice of Mr. Spock, who on dozens of occasions had used the cold clarity of logic and science the save the day, to suggest that he was a possibly nefarious subject of a worldwide conspiracy about science gone mad, was a stroke of genius. Nimoy was also a great foil for series star John Noble, who in a just a few scenes established a real sense of history for the characters.
When Bell vanishes at the end of “Brave New World Part 2,” you realize the incredible mark that Nimoy left on the series in just a handful of appearances. He was truly the right actor for a distinctive role in a series that was unlike any other.
