1. "The Wrath of Khan" (1982): Shatner's performance in this second Star Trek film is considered one of his finest moments as Kirk. The film's emotional depth and the conflict between Kirk and his former friend/adversary, Khan Noonien Singh (Ricardo Montalbán), allowed Shatner to showcase his range as an actor.
2. "The City on the Edge of Forever" (1967): This episode of the original Star Trek series is often hailed as one of the best in the franchise. Shatner's portrayal of Kirk's internal struggle and emotional vulnerability as he faces a temporal anomaly and a chance to change his past is considered a standout moment in the series.
3. "Mirror, Mirror" (1967): In this episode, Shatner plays an alternate version of Kirk from a parallel universe where the Federation is a brutal and authoritarian regime. Shatner's ability to convey the subtle differences between the two Kirks and the inner turmoil of the alternate Kirk as he confronts the consequences of his choices is widely praised.
4. "Space Seed" (1967): This episode introduces the villainous Khan Noonien Singh, and Shatner's confrontational scenes with Montalbán are particularly captivating. The dynamic between Kirk and Khan, with their shared history and clash of ideals, is a highlight of the episode.
5. "Amok Time" (1967): This episode delves into Vulcan culture and Kirk's relationship with Spock (Leonard Nimoy). Shatner's performance as Kirk struggling with his emotions and the pressure of a traditional Vulcan mating ritual is both intense and nuanced.
Overall, William Shatner's portrayal of Captain James T. Kirk in the original Star Trek series remains a benchmark for science fiction performances and has left an enduring legacy in pop culture.