Metroid (species)

Metroids are the titular species of parasitic aliens from the Metroid series. They were created by the Chozo to combat the X Parasites, though they eventually grew out of hand, and are now supposedly extinct thanks to the efforts of Samus Aran.

A Metroid appears as an Assist Trophy in both Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS / Wii U; they also appear as enemies in Smash Run in Super Smash Bros. for Nintendo 3DS. When they appear, they float around the stage, latching on to players and inflicting damage for a time, similar to their series of origin.