The Uecker ([ˈʏkər]) or Ucker is a river in the northeastern German states of Brandenburg, where it is known as the Ucker, and of Mecklenburg-Vorpommern. Its source lies in the Uckermark district, near the village Alt-Temmen. It flows north through Lake Oberuckersee, Lake Mollensee and Lake Unteruckersee, where the old town of Prenzlau stands. Near the small village of Nieden (the border between Brandenburg and Vorpommern) the Ucker changes its name to Uecker.