The Mandelbrot Monk (1999)(users.math.yale.edu)

  Udo of Aachen (c.1200–1270) is a fictional monk, a 
  creation of British technical writer
  Ray Girvan, who introduced him in an April Fool's hoax
  article in 1999. According to the article, Udo was an
  illustrator and theologian who discovered the Mandelbrot
  set some 700 years before Benoît Mandelbrot.

  Additional details of the hoax include the rediscovery of
  Udo's works by the also-fictional Bob Schipke, a Harvard
  mathematician, who supposedly saw a picture of the
  Mandelbrot set in an illumination for a 13th-century carol.
  Girvan also attributed Udo as a mystic and poet whose
  poetry was set to music by Carl Orff with the haunting O
  Fortuna in Carmina Burana.