Thardus

Thardus is an enormous rock monster charged with phazon energy that inhabited Tallon IV in the Phendrana Drifts of the Overworld. It was originally an experiment by the Space Pirates to use phazon to create sentient creatures out of inanimate objects, but was found quarantined in a cavern in Metroid Prime. This experiment was titled "Project Titan".

Battle
Thardus controls the rocks in its domain and the icy weather that resides over the drifts. It can also send ice spikes that encase the enemy in ice, and then Thardus curls up into a ball and attempts to crush it. To defeat the behemoth, Samus must use the Thermal Visor to locate Thardus's weak spot, then fire at it with a weapon, preferably the Wave Beam. Once Samus hits the spot a few times, Thardus will release enormous thermal energy, making the visor "white out". She must then switch back to the Combat Visor and fire at the now phazon-blue weak spot. Thardus will continually switch weak spots until the third weak spot is hit. Then it will unleash an ice storm, making it hard to see in the Combat Visor. Samus must continue the process, until the creature dies once the sixth weak spot is destroyed, leaving behind the Spider Ball.

He also made an appearance in Metroid Prime Pinball, as a boss for the Missile Launcher upgrade, and in Metroid Prime (comic), in the Chozo Ruins.