Okoye was a member of the Dora Milaje, a personal bodyguards and royal security of the Black Panther, recruited from every tribe of Wakanda. In addition with their protective function, they are also a pool of superior Wakandan women for the King to possibly marry.
Marvel Cinematic Universe
Okoye was a member of a Wakandan elite bodyguards known as the Dora Milaje. After the Avengers Civil War, Okoye became Black Panther's personal bodyguard. She accompanied him during his missions, and was present when he was crowned king. However, Killmonger usurped the throne from Black Panther after almost killing him in combat. Though she was briefly forced to serve Killmonger, Nakia made her change her mind and she helped Black Panther take back the throne. After that, she continued to be his bodyguard and appeared to double as his diplomatic escort.