Knight of the Round Table and lover of Queen Guinevere in Arthurian legend (8)
I believe the answer is:
lancelot
(Other definitions for lancelot that I've seen before include "Round Table member" , "One of King Arthur's knights, lover of Guinevere" , "queen's lover" , "Most famous of King Arthur's knights, lover of Guinevere" , "Round Table knight who loved Guinevere" .)