Keilhau is a surname. Notable people with the surname include:
Carl Keilhau (1919–1957), Norwegian journalist and poet Hans Vilhelm Keilhau (1845–1917), Norwegian artillery officer and politician Louise Keilhau (1860–1927), Norwegian teacher and peace activist Wilhelm Keilhau (1888–1954), Norwegian historian and economist Wollert Keilhau (1894–1958), Norwegian librarian and encyclopedist