Diamon Simpson (born September 8, 1987) is an American former professional basketball player working as an assistant coach for the Capital City Go-Go of the NBA G League.

He was a teammate of Australian and Portland Trail Blazers backup point guard Patrick Mills when playing for the Gaels from 2007 to 2009.

From there he signed to play for the Los Angeles D-Fenders of the NBA D-League in 2009–10 where he averaged 15.5 points, 9.6 rebounds and 1.4 blocks in his 30 games.

Simpson was bought out of his D-Fenders contract by the Alaska Aces of the Philippine Basketball Association (PBA) for the 2010 Fiesta Conference (despite a league rule that import players must be no taller than 198 cm).

[12] On December 22, 2018, Simpson returned to Israel for a fourth stint, signing with Maccabi Rishon LeZion for the rest of the season.

[13] On June 10, 2019, Simpson recorded season-highs of 28 point and 20 rebounds, shooting 12-of-17 from the field, leading Rishon LeZion to the Israeli League Final after a 92–86 win over Hapoel Jerusalem.

[16] He subsequently joined Quimsa of the Argentine Liga Nacional de Basquetbol, averaging 11.3 points and 7.9 rebounds per game.