STIII

STIII may refer to:


 * Star Trek III: The Search for Spock (1984 film) third film in the original Star Trek film series
 * Star Trek Beyond (2016 film) third film in the J.J.Abrams reboot Star Trek film series
 * Starship Troopers 3: Marauder (2008 film) third film in the Starship Troopers film series
 * Star Trek III Combat Simulator (1984 game) FASA tabletop board wargame, see Star Trek: Starship Tactical Combat Simulator