Mon Mothma
This cameo was teased in the early trailers for the film. Still, it was nice to see the leader of the Rebel Alliance from "Return of the Jedi." She's played by Genevieve O'Reilly. Originally, O'Reilly reprised her in "Revenge of the Sith," but her scene was cut. It was nice to see Lucasfilm ask her back, and an extra treat for fans.
Bail Organa
We were hoping we'd see Leia's adopted father again after the prequel movies. Jimmy Smits reprises his role and is working with the Rebel Alliance. Eagle-eyed fans may have caught him earlier in the year in a behind-the-scenes video for the film.
Grand Moff Tarkin
You may not have been surprised to see Tarkin since he was hinted at in trailers, but you may have been taken aback and distracted by the heavy use of CG to bring his character to life.
Wayne Pygram played a younger version of Tarkin with prosthetics in "Revenge of the Sith." Lucasfilm went another route this time. Fans are at odds over whether or not CG was the right decision. While some fans enjoyed it, others thought it looked noticeably cartoonish.
Evazan and Ponda Baba
While searching for Saw Gerrera on Jedha, Jyn Erso and and Cassian Andor bump into two ruffians.
If you thought those guys looked familiar it's because Evazan gives Luke a tough time at the Cantina bar in "Star Wars." Ponda Baba wasn't so lucky and lost an arm to Obi-Wan Kenobi's lightsaber
We have a question, though. Exactly how did they get out of Jedha so quickly before it blew to pieces?
Red and Gold leaders
When the Rebel Alliance headed to Scarif, shots from the original "Star Wars" movie were used to add in some of the squad leaders. It was a nice touch since we knew we'd see them again shortly in "Episode IV."
R2-D2 and C-3PO
Of course they're there! In "Star Wars" canon, R2 receives the Death Star plans shortly after "Rogue One" takes place, so it was little surprise to see them pop up briefly in the movie as the rebel fighters head to Scarif.
Leia!
Since "Rogue One" rolls right into "Star Wars," it shouldn't be a surprise that we see Leia pop up at the very end. She needs to get those Death Star plans somehow and send them off in R2-D2.
CG Leia didn't bother us as much as Tarkin, but that's probably because we only see her for a brief moment.