Kettler is a surname of Germanic origins, particularly in Germany and Austria. Notable people with the surname include:
Donald Joseph Kettler (1944 - current) Catholic Bishop of St Cloud.Ferdinand Kettler (1655-1737) Duke of CourlandFrederick Casimir Kettler (1650-1698) Duke of CourlandGotthard Kettler (1517–1587), founder of the Duchy of CourlandJacob Kettler(1610-1682) Duke of CourlandRobert C. Kettler, Washington D.C. area real estate developer (1952- current)Wilhelm Kettler (1574-1640) Duke of CourlandFrederick William, Duke of Courland or Friedrich Kettler (1692-1711)House of Kettler Noble House