What is the name of the droid that helps Jyn Erso in Rogue One?

The story behind the answer

Jyn’s ally is a reprogrammed Imperial KX-series security droid whose blunt humor and brawn make him essential to the Rogue One mission, especially during the Scarif heist. That sets him apart from C-3PO, a gold protocol droid focused on etiquette; R2-D2, a small astromech tied closely to the Skywalkers; and IG-11, a bounty-hunter droid seen in The Mandalorian—not in Rogue One.

Rewired by Cassian Andor, he provides both comic relief and clear-eyed pragmatism, embodying the film’s theme of unlikely heroes. Brought to life by Alan Tudyk’s voice and motion-capture performance, the towering design reflects Imperial manufacture repurposed for the Rebellion—underscoring how stolen tools and sacrifices made the Death Star plans possible.