We're not counting Mon Mothma, picture here, because she has a fairly significant speaking role, but that doesn't give us any shortage in cameos. They include humans, droids, aliens, actors, voices, even other directors.
We should note, too, that there are likely a bunch of the Rogue One crew also appearing in the movie - often, director Gareth Edwards shot in 360-degree environments, and dressed his crew up in full costume, but we couldn't possibly point them out (which means they did a great job). Click through for what we did spot, and see if you found them all, too!
Yes, General Jan Dodonna, who set up the plan for the Battle of Yavin, is there at the table in Rogue One: A Star Wars Story. We saw him in the trailers, so he wasn't exactly a surprise, but it was good to see him and have that direct connection to the original trilogy early on.
Bail Organa appears in the film twice, played once again by Jimmy Smits, reprising his role from the prequels (he has also voiced the character on the animated series Star Wars Rebels). The first time he appears it's an Easter Egg within an Easter Egg - though he's silent, and frankly kind of creepy-lurking in the shadows, when he emerges the Force Theme plays, marking one of the most explicit uses of John Williams-composed music in the film.
Ponda Baba and Dr. Evazan
Hey, those guys on the streets of Jedha look familiar! That's because they're Ponda Baba and Doctor Cornelius Evazan. The characters famously appeared in Star Wars: Episode IV - A New Hope, antagonizing Luke Skywalker and Obi-Wan Kenobi in the Cantina at Mos Eisley. The encounter didn't go well, losing Baba an arm for his friend's harrassment. Robot Chicken did an excellent bit of backstory sketch for the pair that you should watch if you haven't already.
In a blink-and-you'll-miss-him moment also on Yavin at the Rebel Base, Chopper, the lovable grumpy droid from Star Wars Rebels appears. Seriously, it's a very quick cameo, so don't blink at all when you're watching the movie. NO BLINKING.
R2-D2 and C-3PO
Barely an Easter Egg, but certainly a cameo, R2-D2 and C-3PO, the only characters to appear on screen in every Star Wars film, make their requisite appearance at the base at Yavin. Even at the press screening, people cheered for their brief moment.
"Now they're going to Scarif? Why does no one tell me anything?" C-3PO complains. R2-D2, meanwhile, whistles, beeps, and wiggles excitedly. You may not have heard or hear any lines there, because if your theater was anything like the ones ComicBook.com staff were in last night, the cheers and claps for the pair drowned out all other sound.
Also appearing in the film are the aforementioned Chopper and Mouse droid, plus a shiny RA-7 protocol droid - you may know the droid AP-7, an RA-7 model, from Star Wars Rebels. Various other astromechs appeared, naturally, when the X-wing squadron was flying off to battle.
Yes! The Gold Leader seen in Rogue One is the same Gold Leader at the Battle of Yavin in Star Wars: Episode IV - A New Hope. The character Jon Vander held the designation in both battles, it seems. Vander, incidentally, is from Onderon, the same planet as Saw Gerrera. Red Leader, and the voice of some of the other pilots, were returned cameos as well.
Princess Leia and the Tantive IV
Princess Leia appears in her signature ship, the Tantive IV, at the end of the film, bringing the story full circle. There will probably be some debate over how she was included and presented, but she's there none-the-less.
Clone Wars and Rebels Voice Actors
As always, Lucasfilm went to their pals and long-term voice actors for some ADR, adding in the voices of the stormtroopers and random members of the Rebel Alliance. That included David Collins, who has done both audio and voice work for Lucasfilm (and the former Lucas Arts) for years, Steve Blum, who currently voices Zeb on Star Wars Rebels (and does trooper and rebel voices there, as well), Dave Filoni, the showrunner of Star Wars Rebels and Star Wars: The Clone Wars before it, and Vanessa Marshall, who plays Hera on Rebels.
Clone Wars veterans Fred Tatasciore (Various monsters - you may know him best as the Hulk in several animated series, movies, and games, though), James Arnold Taylor (Obi-Wan Kenobi), Sam Witwer (Darth Maul - also on Rebels of course), Matthew Wood (the Droids), and Tom Kane (Yoda) were all voices in the film, as well.
Tony Gilroy, brother of John Gilroy who edited Rogue One (and also did some ADR), and producer of Nightcrawler, a film starring Riz Ahmed, did some ADR work, too.
David Ankrum, an ADR voice actor from A New Hope, voiced the Yavin intercorm in the film. The rest of the full list, in alphabetical order:
David Acord, Steve Bardack, Verona Blue, Dave Boat, Eugene Byrd, David Cowgill, Jonathan Dixon, Michael Donovan, Terri Douglas, Robin Atkin Downes, Michael Giacchino (composer of the film), Tom Harrison-Read, Kevin Hickman, Karen Huie, Lex Lang, Vanessa Lengies, Yuri Lowenthal, Alexi Melvin, Flora Miller, William M. Patrick, Christopher Scarabosio, Orly Schuchmacher, Kat Sheridan, Christian Simpson, David Sobolov, Julian Stone, and John Swartz.
He's in all three trilogies of films, and now Warwick Davis is in the standalones, as well. The actor, who played Wicket the Ewok in Return of the Jedi, continues his W-named character string in Rogue One, playing Weeteef Cyubee, the alien character with a big gun that works for Saw's rebels on Jedha, as seen in the ambush scene there.
Weeteef follows Wollivan in The Force Awakens, both Wald and Weazel in The Phantom Menace, and, again, Wicket in the original trilogy. He'll be back in Episode VIII, as well.
Episode VIII director Rian Johnson (and his assistant)
As reported back at Star Wars Celebration Europe, Star Wars: Episode VIII director Rian Johnson and Rogue One director Gareth Edwards swapped cameos in each other's films.
Johnson chose a key member of the Death Star crew as his cameo.
"We're each one of the guys in the firing chamber of the Death Star," alongside his assistant, and he said he would be "pulling the lever."
Directors Phil Lord and Chris Miller, who are heading up Han Solo, were on set and costumed up for Rogue One, but had to leave set before they could be shot on film.
Female X-wing Pilots
This is a strange bit of cameo action, but interestingly, there were female X-wing pilots in the original Star Wars - they just didn't make it in the movie, as they were cut from the film in the edit bay. There they are in the Battle of Scarif, piloting, finally. As a bonus, if you listen closely it sounds like the aforementioned Vanessa Marshall, who voices Hera on Star Wars Rebels, is one of those rebel pilots. Glorious.