Memmert is a small East Frisian island off the northern coast of Germany, with an area of 5.2 square kilometres (2.0 sq mi).^[1] Memmert is uninhabited, with only one house on the island for wildlife-spotting purposes.^[2] Occasionally, some guests from the neighboring islands visit Memmert for recreation. Memmert is officially a wildlife protected area.

The island plays an important role in Erskine Childers's novel, The Riddle of the Sands (1903).^[3]