Killen is a surname. Notable people with the surname include:
Louis Killen or Louisa Jo Killen (1934-2013), English Folk Singer
Chris Killen (born 1981), New Zealand professional footballer
Edgar Ray Killen (born 1925), American criminal
James Killen (1925-2007), Australian politician
John Sidney Killen (1826-1903), American farmer and state legislator
William Dool Killen (1806-1902), Irish Presbyterian minister and church historian
William M. Killen, (born 1938), American politician
William Wilson Killen (1860–1939), Australian politician
