Villain in King Lear (6)
I believe the answer is:
edmund
(Other definitions for edmund that I've seen before include "One of two kings of England, d. 946 and 1016, respectively" , "St. - - the Martyr" , "- Ironside, English king" , "Part of 1 25 [KING LEAR]" , "Kean, Spenser or Ironside" .)