Thomas Petrus A. Koenis (born 11 December 1989) is a Dutch retired basketball player.

In international play, Koenis represented the Netherlands men's national basketball team in 41 games.

When the Giants also decided to leave the Dutch Basketball League in 2011, Koenis signed a 3-year contract with the GasTerra Flames from Groningen.

[4] On 10 January 2018, Koenis scored 25 points while shooting 9/9 from the field, accumulating an efficiency rating of 36 in a 109–69 win against Keravnos in the FIBA Europe Cup.

[7] On 6 December 2022, Donar retired Koenis' jersey number 14, while also naming a stand in the MartiniPlaza after him.