Sentinel
this immense beast was found on the planet Alashan. Roughly humanoid in shape, the Sentinel stood well over two meters in height, and had crustacean-like armor plating protecting its body. When it was attacked by agents of both the Alliance and the Empire, the Sentinel showed a remarkable resilience to energy weapons and physical damage, surviving even when it was caught beneath several tons of rubble in an explosion. The Sentinel could also be summoned instantly to another part of the city, and had the ability to alter its size to fit its environment. Luke Skywalker later discovered that the Sentinel creature was a beast of pure energy, created by the ancient inhabitants of Alashan to protect their underground city. When the controls panels which maintained the underground city were destroyed, the Sentinel creature lost much of its power, as its connection to the planet's own energy was broken. Luke then dispatched the Sentinel with a stab of his lightsaber.