Scientifically known as the Mysticeti, the baleen whales, also called whalebone whales or great whales, form a suborder of the order cetacea. The distinguishing feature between this suborder and the toothed whales is that baleen whales have baleen plates instead of teeth in the upper jaw, which enables them to filter food from water. Teeth are present only during the embryonal phase, except for fossil baleen whales which yet had teeth instead of baleen.

Baleen whales are generally larger than toothed whales, and the females are larger of the two sexes. This group comprises the largest living animal species. Baleen whales have two blowholes, causing a V-shaped blow.

The suborder contains four families and fourteen species. A list of species can be found below and at the cetacea article. Its scientific name derives from the Greek word mystax, which means "moustache."