K9999 (pronounced "K Four-Nine") is a video game character in The King of Fighters series who debuts as a member of the NESTS team in The King of Fighters 2001.

His character design is heavily inspired by the character Tetsuo Shima from the 1988 animated film Akira. His name is a homage to a character in the anime, Armored Trooper Votoms. He was believed to be copyrighted by Eolith though SNK has expressed public disfavor for K9999 -presumably due to the explicitness of his tribute- and it is unlikely he will appear in the future. In a 2005 poll made by SNK-Playmore USA, he was voted as the seventh fan favorite character with a total of 156 votes.

He is voiced by Nozomu Sasaki, who happens to be the same person who voiced Tetsuo in the Japanese version of Akira.

He is 16 years old officially.