The P90 is a Belgian-designed PDW (Personal Defense Weapon), developed between 1986–1987 by Stéphane Ferrard at Fabrique Nationale de Herstal. It fires 5.7x28mm ammunition from an axially-mounted 50-round box magazine. It is designed for defense during close quarters or medium to short range combat.
While most other bullpup designs are unsuitable for left-handed firing (as empty cartridge cases are normally ejected to the right, and would risk hitting a left-handed shooter's face), the P90 is fully ambidextrous due to ejecting spent cartridges out the bottom.
Due to its distinctive futuristic looking shape and relatively small size, the P90 has become fairly common in Science fiction and military action anime, video games, and live-action series.
This tag implicates submachine_gun and bullpup (learn more).