Ostrach is a municipality in the district of Sigmaringen in Baden-Württemberg in Germany.
Ostrach may also refer to: Simon Ostrach (1923–2017), American academic scientist Ostrach (Iller), a river of Bavaria, Germany, tributary of the Iller Ostrach (Danube), a river of Baden-Württemberg, Germany, tributary of the Danube Battle of Ostrach, occurred on 20–21 March 1799