One cameo, or two, depending how you look at it was hyped before the movie came out, especially in England. It had been revealed that Prince Harry and Prince William portrayed Stormtroopers in The Last Jedi and they were really excited about it. However, don't go looking for them in the final cut as Rian Johnson had to snip their part out at the very last minute, which has been confirmed by John Boyega. Fear not, the Prince cameos will more than likely be featured prominently in the deleted scenes area of the DVD/Blu-ray release. Better luck on Star Wars 9, guys.
Yes, that Mark Hamill, the guy who plays Luke Skywalker has a cameo in The Last Jedi and probably not the one that you're thinking about. Yes, Hamill portrays the old and bad beard dye "younger" Luke, but he also has another role that was revealed for those who stuck through the credits of the movie. Mark Hamill is listed as playing the mysterious Dobbu Scay character, but just who is Mr. Scay? We have a pretty good idea and that will be discussed further very soon. But for now, let the speculation begin.
Any fans of Rian Johnson before The Last Jedi know that he is an incredibly loyal person and often includes a lot of the same actors/friends in all of his movie. Joseph Gordon-Levitt has the rare distinction of being in every Johnson movie released thus far. Gordon-Levitt confirmed his cameo in The Last Jedi via social media and it has now been revealed that he voices the role of alien Slowen Lo in the movie. The Visual Dictionary expands on the curmudgeonly character, revealing he "made a fortune selling driftwood sculptures" and now lives by the beach, which explains his anger at the rebels. Slowen Lo is another nod to the Beastie Boys, with the first being Ello Asty in The Force Awakens.
Justin Theroux is one of the easier cameos to spot in The Last Jedi, and that makes the sexually awkward comments of Maz Kanata easier to understand, though a tad gross nonetheless. Theroux is the Master Codebreaker with the red broach on Canto Bight who Rose and Finn are seeking before they are thrown in jail for a parking violation. He's only on the screen for a brief moment, but he's there and now all we can think about is him getting nasty with Maz. Thanks, Rian Johnson. Although he's in the movie for just a few seconds, shown as a James Bond-esque casino player, thanks to The Visual Dictionary we learn a bit more about the character. Known only as Master Codebreaker, he's something of a legend on Canto Bight, as he is banned from playing any electronic games in the casino, forced by the management to only play dice.
British fashion model Lily Cole also has a cameo, playing Party Girl. Cole has dabbled in acting before and is probably best known for her central part in The Imaginarium of Doctor Parnassus. Cole can be seen standing next to Justin Theroux's Master Codebreaker character during the Canto Bight scenes. According to the Visual Dictionary, her real name is a mystery, which follows a pattern of most of the guests at the casino, but she goes by the name Lovely.