K-2SO

"The captain says you're a friend. I will not kill you."

- K-2S0 to Jyn

K-2S0 (sometimes spelled Kaytoo Esso or Kay-Tuesso) is a character who appears in the Star Wars film, Rogue One. K-2S0 was originally an enforcer droid created for use in the Galactic Empire's armed forces, until at some point he encountered Captain Cassian Andor, who was able to reprogram him to serve the Rebel Alliance.

Along with a band of roguish Alliance operatives, K-2S0 went on a daring mission to steal the plans for the Empire's ultimate weapon, the Death Star.

Rogue One
K-2S0 first appears to rescue Jyn Erso from an Imperial labor camp. He accompanies Cassian and Jyn to find Saw Gerrera on Jedha, who had been close to Jyn's father Galen.

On Jedha he is told to stay with the ship, but later reappears to help Jyn and Cassian to fight off Stormtroopers after Saw Gerrera's henchmen make an attack on an Imperial cargo transport. He later helps them out of Jedha.

On Eadu he is told to stay with the ship, which he does. He later agrees to accompany Jyn to obtain the Death Star plans, and on Scarif imperial base he communicates to Cassian and Jyn the location of the Death Star plans in the control room. He tries to fend off attacking Stormtroopers but eventually succumbs due to multiple shots from them.

Trivia

 * K-2SO's name was first revealed in a preview of Rogue One: A Star Wars Story: The Official Visual Story Guide, though the source listed him as both "K-2SO" and incorrectly as "K-250".