The Great Bittern (Botaurus stellaris) is a wading bird of the heron family Ardeidae.

It is a large, chunky, brown bird, very similar to the American Bittern, Botaurus lentiginosa. It is 69-81 cm (24"-34") in length, with a 100-130 cm wingspan.

It is declining in much of its temperate European and Asian range. It is resident in the milder west and south, but migrates south from areas where the water freezes in winter.

This bittern is usually well-hidden in Phragmites reedbeds. Usually solitary, it walks stealthily seeking amphibians and fish. If it senses that it has been seen, it becomes motionless, with its bill pointed upward, causing it to blend into the reeds. It is most active at dawn and dusk.

Its folk names include barrel-maker, bog-bull, bog hen, bog-trotter, and butterbump, mostly refer to the mating call of the male, which is a deep fog-horn or bull-like boom. The Latin for bittern, Botaurus, also refers to the bull. The other part of its scientific name, stellata is the Latin for starry, in reference to its plumage.