Greef Karga was a human male and former disgraced magistrate before joining as a rebel agent of his friends. He eventually met with the bounty hunter named Din Djarin in a cantina to accept four bounties the hunter had captured.
Karga was pleased when Djarin's work and gave him a new bounty, the child Grogu. Despite Djarin's change of heart regarding this bounty, he and Karga later became good friends.
Karga eventually became the unofficial magistrate of a city on some planet (can't remember the name) and he asked Din Djarin to be his personal enforcer. He refused but Djarin's other companion, Cara Dune, accepted the offer with Karga becoming a Magistrate.