The European otter (Lutra lutra), also known as the Eurasian otter, Eurasian river otter, common otter and Old World otter, is a European and Asian member of the Lutrinae or otter subfamily, and is typical of freshwater otters.

The European otter is a typical species of the otter subfamily. Brown above and cream below, these long, slender creatures are well-equipped for their aquatic habits. This otter differs from the North American river otter by its shorter neck, broader visage, the greater space between the ears and its longer tail. However, the European otter is the only otter in its range, so it cannot be confused for any other animal. Normally, this species is 57 to 95 cm (23-37 in) long, not counting a tail of 35-45 cm (14-18 in). The female is shorter than the male. The otter's average body weight is 7 to 12 kg (15.4-26.4 lbs), although occasionally a large old male may reach up to 17 kg (37 lbs). The record-sized specimen, reported by a reliable source but not verified, weighed over 24 kg (53 lbs).