Jyn’s estranged father, Galen, is the galactic version of a nuclear pioneer. He’s a scientist, and he is the scientist who supposedly helped to create the original Death Star from the plans the Geonosians gave Darth Sidious/Emperor Palpatine.
According to his own personal entry in Wookieepedia: His knowledge of the universe led both the Empire and the Alliance to Restore the Republic to seek him out. His estranged daughter, Jyn Erso, later became part of the Rebel mission to steal the plans to the Imperial super-weapon, the Death Star.
The real question remains: Does Galen help his daughter steal the plans? Or, is he an Imperial sympathizer, and does he try to turn her over to the Empire? I guess we wait until December to find out.
Next: Diego Luna as Captain Cassian Andor