Ulysses Klaue is a Belgian smuggler with a strong desire for Vibranium. He was among those who have searched for the source of the vibranium and when he discovered that it was in Wakanda, Africa, he eventually recieved help from N'Jobu who provided him and his men with safe passage on infiltrating the country. Successfully having taken a quarter ton of vibranium, Klaue was eventually branded by the wakandans as a theif before escaping with his life.
Years later, he was approaced by Pietro and Wanda along with Ultron who came to do business with him on buying all the vibranium he's got in exchange for the funds Ultron transfers to his account from Tony Stark's. But when Klaue asked the android if he was one of Tony's inventions, Ultron got edgy and severs the smuggler's left arm before making use of his men attacking the Avengers.
Klaue eventually got his arm replaced with an arm cannon a year later when he started working with N'Jobu's son N'Jadaka, going by Erik Stevens as the two villains and their operatives robbed a British Museum of a mis identified Wakandan artifact while making sure the crime scene was spread out to avoid suspicion.
Next day, Klaue arrived in Basan, South Korea with plenty of henchmen for protection to do business with the higest bidder who in this case; Everett Ross. But when Okoye got impatient, she blew her cover as Klaue escapes the club using his sonic arm cannon for defense. Next he and his convoy were pursued by the wakandans and despite his efforts of loosing them, the new Black Panther/T'Challa caught him. T'Challa attempted to kill Klaue for all the people he murdered in his country but was stopped by Nakia over all the Koreans and tourists watching him.
Next morning, Klaue caught a case of the giggles as Ross interrogated him. After Klaue advised Everett to ask T'Challa for proof that Wakanda has more vibranium in his country, Erik Killmonger and his men arrived, attacking everyone in the facility while rescuing Klaue.
Klaue was glad that Stevens rescued him that he was more than willing to pay him for his service once they returned to South Africa. But when Killmonger requests that Klaue should drop him and his team off at Wakanda and with the smuggler not wanting to risk it, his denial provokes Stevens into shooting one of his own teammates, driving Klaue into holding Linda at gunpoint, hoping that Erik will stand down from his hostile act. But all because of the trauma of his dead father N'Jobu, N'Jadaka kills his own girlfriend instead of saving her before subduing Klaue and sparing his life for a minute to prove why he isn't afraid to go to Wakanda before shooting his father's client dead, undoing the deceased prince's mistake.
Killmonger eventually met up with W'Kabi at the border and by handing Klaue's corpse over to him and the Border Tribe, it made the two orphans easy allies.