Osterman or Ostermann is a surname, and may refer to
- Alexander Ivanovich Ostermann-Tolstoy
- Andrei Osterman
- Cat Osterman
- Edward Albert Ostermann
- Harry Osterman
- Ivan Osterman
- Manfred Ostermann (1958–), German local politician (independent) and district chief executive (Landrat)
- Max-Hellmuth Ostermann, German WWII Luftwaffe Ace