Star Trek: The Original Series had three lackluster season finales. With its premiere in 1966, Star Trek introduced the world to Captain James T. Kirk (William Shatner) and the Starship Enterprise, launching what would one day become a massive franchise. Over the course of Star Trek's three seasons, Captain Kirk, Mr. Spock (Leonard Nimoy), and Dr. McCoy (DeForest Kelley) became one of television's most beloved trios as they boldly explored the galaxy. While TOS delivered many iconic episodes, none of its three season finales were particularly memorable.