1. SAW GERRERA (played by Forest Whitaker)
That is really cool to me that the new Movie integrate a great character that we have seen in the Clone Wars animated serie ! Finaly some links to the past before episode IV. (I mean Rogue One takes place actually between Episode III and IV so it make sense...).
Saw Gerrera is a very tough rebel of the planet Onderon. We can see the story in a 4 episodes arc of Season 5. Separatists are taking over the planet by occupying the main city and arresting the leader.
Saw (and his sister) are lightning up the resistance and start with guerrilla over the droid army. However the methods of Saw are quote extreme and whose aggressively is not fully approved by the Jedi Order (that is secretly supporting the rebellion). Saw and his warriors have been trained by Anakin Skylwaker, Ashoka Tano and commander Rex !
But the freedom of Onderon was recovered at a very high personal cost for Saw (I will not make spoiler on that).
We also know from Canonic information that afterward Saw is the leader of the "partisans" that are a group of rebels fighting now agains the Empire.... again with no full approval of the fighting ways from the MonMothma rebellion.
These tuff methods are indirectly described in the other animated series: Rebels in Season 2 "The honorable Ones": Imperial Agent Kallus explains that Saw used also mercenaries with no mercy...
"I'm not a terrorist. I'm a patriot. And resistance is not terrorism."
So it is a tuff warrior that suffered and paid very high cost from continues war. He is also a great motivator and really concentrate on his goal.
As a consequence, when we hear him saying in the trailer : "if you continue to fight, what will you become?" he is probably talking to Jyn but referring to what happened to himself ! That is pretty interesting.
I find the involvement of this character from Clone War animated series really a good choice to make bridges between all the stories ! GREAT MOVE !
(It recalls me the appearance of the young Tarkin in Clone Wars! That was also fantastic idea)