1) Welsh mythology 
Efnysien fab Euroswydd (also spelled Efnissien or Efnisien) is a sadistic anti-hero in Welsh mythology, appearing prominently in the tale of Branwen ferch Llŷr, the second branch of the Mabinogi. Described by Will Parker as `a study in the psychopathic personality` and an `embodiment of the forces of anti-social disruption,` he is the catalys...