John Edward H. Rulloff (also known as Ruloff, Rulofson, or Rulloffson, as well as several aliases; 1819/1820 – May 18, 1871) was a Canadian-born American doctor, lawyer, schoolmaster, photographer, inventor, carpet designer, phrenologist, and philologist, in addition to a career criminal and serial killer. This dichotomy was exemplified in the title of his 1871 biography, The Man of Two Lives. He was also known as "The Genius Killer".