Koo Kien Keat AMN (Chinese: 古健傑; Pe̍h-ōe-jī: Kó͘ Kiān-kia̍t; born 18 September 1985) is a Malaysian former professional badminton player.

He succeeded in both men's and mixed doubles but is best known for his partnership with Tan Boon Heong with whom, he reached a career high ranking of world number 1.

En route to the finals, they defeated several top pairs including Markis Kido and Hendra Setiawan of Indonesia.

They also won their first All England Superseries title after beating Chinese pair, Cai Yun and Fu Haifeng in straight games.

At the 2010 BWF World Championships, the pair entered the semifinals after beating Korean rivals Jung Jae-sung and Lee Yong-dae.

They came in seeded number 1 in the All England Open but lost in the first round to Denmark former world champions Lars Paaske and Jonas Rasmussen.

In the 2010 BWF World Championships, they beat the young Chinese pair of Chai Biao and Zhang Nan in the quarter-finals and later their arch rivals, the South Koreans Jung Jae-sung and Lee Yong-dae, in 3 sets to reach the semi-finals.

At the 2011 All England Open, Koo and Tan defeated 2008 Olympic champions Markis Kido and Hendra Setiawan in the quarterfinals.

[1] In 2013, they suffered a series of early round exits in 2013 and a three-year major title drought but managed to remain in the top 10 of the world rankings.

In August that year, Koo returned to play his last tournament with Tan at the 2014 BWF World Championships in Copenhagen, Denmark.