Koester is a surname. Notable people with the surname include:
Bev Koester (1926–1998), Canadian naval officer and civil servant Bob Koester (1932–2021), American music producer Charles Roman Koester (1915–1997), American Catholic bishop Hans von Koester (1844–1928), German admiral Helmut Koester (born 1926), American theologian Jolene Koester, president of California State University, Northridge
See also Koester, Missouri Köster