Four-dimensional space whales

Four-dimensional space whales are cetacean-like alien creatures. They resemble s, feed on the obsession of others, and into the Universe to hunt and fill their lungs with vacuum. When not in Universe Gamma, the whale lives in the fourth dimension, a realm where the laws of reality are radically different than they are here.

The first Planet Express crew came across an albino space whale in 2961 and was eaten by it; 50 years later, the current Planet Express crew encountered it while delivering a monument dedicated to the first crew. The whales can be controlled if the obsession they are feeding on becomes overpowered by another obsession, such as when Leela overpowered Möbius Dick due to her desire to finish her delivery.