Thardus is a towering creature made out of rocks that appears as a boss in Metroid Prime.
Appearing in the Phendrana Drifts of Tallon IV, Thardus is the result of a Space Pirate experiment to create living weapons from inorganic matter by infusing the inanimate material with Phazon radiation. The experiment was labelled "Project Titan".
Thardus' form consists of dozens of boulders which are held together by a Phazon radiation field. Space Pirate logs and Samus Aran's scan of the creature when she battles it label Thardus as sentient, although the creature does not display any sign of intelligence and only responds violently when approached by other life-forms. The Pirates' attempts to tame the beast all ended in failure and so the monster was quarantined in a cavern where it remained dormant until the arrival of Samus Aran. When Samus entered the cave, Thardus awoke and attacked her.
Thardus controls the rocks in its domain and the icy weather that resides over the drifts. Its primary attack is to animate three small rocks and cause them to rush at Samus. These rocks can be destroyed for ammo and energy. It can also slam its fists into the ground and send an ultrafrigid wave at Samus that will freeze her on the spot, and lastly Thardus will curl up into a ball and attempt to crush its victim.
To defeat the behemoth, Samus must use the Thermal Visor to locate Thardus's weak spot, then fire at it with a weapon, preferably with a single Super Missile. Once Samus hits the spot a few times, Thardus will release enormous amounts of thermal energy as its Phazon core is exposed, making the visor overload. Alternatively, Samus can wait until the beast begins to roll around the room. At this point, laying a single Bomb in its path will instantly smash open the weak point.
Regardless of how the Phazon core is exposed, Samus must then switch back to the Combat Visor and fire at the 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. After the sixth weak spot is destroyed, the creature will dispel the ice storm, so visibility returns to normal. It also noticeably speeds up at this point, as it only has one more weak point that must be attacked. Samus must continue the process, until the creature explodes once the seventh weak spot (which incidentally takes more hits than the others) is destroyed, leaving behind the Spider Ball. Humorously, a large rock hits Samus in the head after she moves out of the way of the falling boulders, making a sound similar to that of a metal drum.