K-2S0

K-2SO or K2 was a former imperial droid who was reprogrammed to be a snarky slave, I mean freind of Captain Cassian Andor. K2 had a sence of humour, telling Jyn Erso that he would not kill her, even though he wanted to and dreamed about it.

Biography
Ar some point he was bulit by some drunken trandoshans useing a stolen Transformer design.