The arms dealer who got into Wakanda before anyone else did, took a quarter of a ton of vibranium out, and never stopped enjoying it.
Ulysses Klaue is the character both of his films use as a key: he is the only outsider who has stolen from Wakanda and lived, which makes him proof that the country’s whole security policy has already failed once.
Andy Serkis plays him as a man having a wonderful time, which is rare in these films and is why the Busan sequence works. His arm is a Wakandan mining tool he turned into a weapon, which is the joke of the character in one object.