The Big Bang Theory: 10 Best Characters Who Only Appeared In One Episode
3. Mark Hamill (Himself)
Episode: "The Bow Tie Asymmetry" (Season 11, Episode 24)
On the eve of Sheldon and Amy's wedding, Howard finds a lost dog. The dog's owner swings by Howard's home to pick up his pooch and it's revealed to be none other than Mark Hamill! Howard manages to talk the Star Wars actor into officiating the wedding of the socially awkward soulmates, much to the delight of every nerd in attendance.
A monumental event like Sheldon and Amy's wedding deserved a guest star to match, and Mark Hamill was the perfect choice. Not only did his appearance tick a major nerd box, but the episode also gave Hamill a chance to show off his many talents: his comic timing, his heartfelt authenticity, a bit of his scary anger, and (for good measure) a very cute dog. What's more, he's given more screen time in this episode than in the entirety of Star Wars: The Force Awakens.
It was just a generally awesome one-off appearance and well worth the 11-year wait. Although, we would expect nothing less from a Jedi Master.