Mayan Keer Kiir (born 1 January 1998) is a South Sudanese-American professional basketball player who last played for the Westchester Knicks of the NBA G League.

Kiir was born in South Sudan but fled the country when he was four, along with his mother and siblings, leaving his father behind who was fighting in the Second Sudanese Civil War.^[1]

The family moved to Melbourne, Australia, where Kiir started playing for the development team Longhorns where he was discovered by coach Manny Berberi.^[2] He then earned a scholarship to play high school basketball for Victory Rock Prep in Florida.^[3] He led his team in scoring and rebounding in his senior season.

Kiir played for LSU in his first college season, for South Florida in his second and after a transfer year he played for New Mexico State.^[3] He was also on the roster for Central Baptist College during the 2021–22 season and played his last game on January 13, 2022.^[4]

On April 9, 2022, Kiir made his professional debut with Cobra Sport in the Basketball Africa League (BAL).^[5] He had a double-double of 18 points and 22 rebounds in a loss to Zamalek, setting a league record for most rebounds in a game.^[6] Kiir averaged 18.8 points and a league-leading 11.2 rebounds in five games in the Nile Conference, as Cobra finished in the fifth place.

Kiir is the cousin of Mangok Mathiang, a professional basketball player who has played for the National Basketball Association (NBA) team Charlotte Hornets.^[3]