Darth Nihilus was a dog who was constantly hungry and intended to feed on all life in the galaxy. On his first birthday, he ate an entire planet, and on occasions when he ran out of dog food on his vessel, the Ravager, he ordered his apprentice, Darth Haagen-Dahz, to bring him more food.
The dark dog kept his dog-status hidden from others by disguising himself in a black cloak and wearing a mask made from old chewing toys. To complete the disguise, he stood on stilts to make himself appear taller.
Nihilus had an eccentric habit to chase starships. One particular ship he chased was the Ravager, which had been been buried in the depths of Malachor V. He tore it from the surface and brought it back into known space.