The Black Elster[1][2] or Schwarze Elster (German, pronounced [ˌʃvaʁtsə ˈʔɛlstɐ] ⓘ; Lower Sorbian: Carny Halšter; Upper Sorbian: Čorny Halštrow) is a 179-kilometre (111 mi) long river in eastern Germany, in the states of Saxony, Brandenburg and Saxony-Anhalt.

The Black Elster flows through the cities Kamenz/Kamjenc, Hoyerswerda/Wojerecy, Senftenberg/Zły Komorow, Lauchhammer, Elsterwerda, Bad Liebenwerda, Herzberg and Jessen.

The river rises in the Lusatian Highlands (Upper Lusatia) about 1.5 kilometres (0.9 mi) south of the village Kindisch in the borough of Elstra on the eastern flank of the 396-metre (1,299 ft) high Kuppe, a subpeak of the Hochstein.

Further downstream, after 63 kilometres (39 mi), it crosses the Saxon-Brandenburg border and flows through Senftenberg, Ruhland and Lauchhammer to Elsterwerda.

Field Marshal Blücher crossed the Elbe River near its confluence with the Black Elster on 3 Oct 1813 on his march to Leipzig.