According to reports, Alan Tudyk's role in Rogue One: A Star Wars Story has been revealed. Needless to say, this article may contain spoilers!
Making Star Wars reports that Alan Tudyk's role will be that of an Enforcer Droid, who's appearance is said to resemble a mash-up of Warner Bros.' Iron Giant and EV-9D9 from Return of the Jedi. Rather than the cuteness we saw in BB-8's design for The Force Awakens, Tudyk's Enforcer Droid is an apparent evolution of the Clone Wars era Super Battle Droids, reflecting the grittiness of Rogue One.
The Enforcer Droid is apparently an ex-Imperial droid that has been captured and reprogrammed to serve the Rebel Alliance as they carry out their mission to steal the Empire's plans for the dreaded Death Star.
For a full description of the character, check out the original article on Making Star Wars.
Rogue One is set for release on 16 December 2016.