Bahnsen is a German surname. Notable people with the surname include:

• Greg Bahnsen (1948–1995), Calvinist philosopher, apologist, and debater
• John Bahnsen (born 1934), United States Army general
• Julius Bahnsen (1830–1881), German philosopher
• Karen Bahnsen (born 1960), American college golf coach and former player
• Ken Bahnsen (born 1930), American football player
• Stan Bahnsen (born 1944), Major League Baseball pitcher
• Uwe Bahnsen (1930–2013), German car designer

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