Istvan is the Hungarian form of Stephen meaning "crown". In the works of Harry Turtledove, Istvan may refer to:

Characters with the name Istvan:

Istvan (Gyongyosian), a soldier and POV in Darkness.
Istvan Polgar, the once-mentioned father of Esther Sullivan in Joe Steele.
Istvan Szolovits, fictional Hungarian soldier and POV in The Hot War.