The IG-series assassin droid that saves the Mandalorian in Season 1 is IG-11. After being rebuilt and reprogrammed, the droid rescues Grogu, protects Din Djarin’s group, and helps them escape Imperial forces.
Din first encounters IG-11 on Arvala-7, where both bounty hunters are pursuing the same mysterious Child. IG-11 initially intends to kill the target after capture, so Din shoots and destroys him. The Ugnaught Kuiil later repairs the droid and changes its programming to nurse and protect rather than assassinate.
In “Chapter 8: Redemption,” IG-11 catches up with the scout troopers who abducted Grogu, defeats them, and rides into town to save Din, Cara Dune, and Greef Karga. He treats Din’s severe injuries and removes his helmet, correctly noting that a droid is not a living thing.
IG-11 ultimately sacrifices himself by detonating near an Imperial ambush. He is distinct from IG-88, another assassin droid from the wider Star Wars universe, and from the later IG-12 exoskeleton used by Grogu.