Paralyzer
The Paralyzer is Zero Suit Samus' neutral special move. Its main purpose is to stun opponents, but it also deals some damage. It can also be charged to increase the time an opponent is stunned.
The Paralyzer is also used as her down smash, apparently with a similar effect (although fired downwards).
Interestingly, the stunning effect caused by the Paralyzer is not affected by knockback resistance. Also, hitting a non-flinch character like Porky with this will cause them to shake like being paralyzed, but will of course still move.
In Metroid: Zero Mission, Zero Suit Samus' role in the game is a stealth role; even with a charge shot, the best she can do with her gun is paralyze Space Pirates for a few seconds, but in Metroid Other M, an uncharged shot paralyse the enemies and a charged one can destroy them.
