Raiden is a character from the Fatal Fury Fighting Game Series. Raiden appeared the first time in Fatal Fury and returned in Fatal Fury 2, in Capcom Vs SNK 2 he made a comeback as a playable character. Maybe SNK thought that it was a good reason to put Raiden into  the King of Fighters series since KOF XII

 

See also: Fan Art of Raiden (FF) on Game-Art-HQ (not yet)

 

King of Fighters XIII (2010)

King of Fighters XII (2009)

 

Capcom Vs SNK 2 (2001)

 

Capcom Render

 

SNK Render