Bodhi Rook is a human cargo pilot from Jedha who defects from the Imperial military to carry Galen Erso's message to Saw Gerrera, setting the plot of Rogue One: A Star Wars Story (2016) in motion. Riz Ahmed plays him.
He is the inciting incident
Everything in the film follows from a decision he has already made before the audience meets him. Galen persuades him to defect; Bodhi flies out with the message about the reactor module; the message reaches Saw; Saw's possession of it brings in Jyn Erso and Cassian Andor. Without the pilot there is no Rogue One and, in a real sense, no Yavin.
What Saw does to him
His reward for defecting is to be interrogated by Saw's Bor Gullet, a creature that extracts truth from a mind and leaves it disordered. When we meet him properly he is shaking, repeating himself, struggling to hold a thought — and the film asks him to keep functioning anyway. It is a pointed piece of writing: the rebellion damages him before the Empire gets the chance.
Scarif
He recovers enough to fly the stolen shuttle to Scarif, talk his way past the shield gate with a callsign he invents on the spot, and then get the transmission link open on the beach so the plans can leave the planet. He is killed by a grenade seconds after succeeding. Of the six, his is the death with the clearest causal line to the Death Star's destruction.