“Mark Hamill’s role as Luke Skywalker was pretty brief in ‘Star Wars: The Force Awakens.’ In fact, it was so small that Mark Hamill apparently found something else to help keep him busy as he actually has an additional uncredited role in the film. Eagle-eyed viewers of ‘Star Wars: The Last Jedi’ will have seen Mark Hamill’s name in the credits twice. Recently, the actor was asked about his second role as an alien creature, and he talked about his love for the work of motion capture artists like Andy Serkis, and the fact that ‘The Last Jedi’ wasn’t the first time he had done it.”
You can read more at Cinema Blend.