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
See also ST3 (disambiguation)