"A brilliant personification of the very essence of fanaticism," per the book "Melville: His World and Work" (4)
I believe the answer is:
ahab
(Other definitions for ahab that I've seen before include "Captain hunting Moby Dick" , "One whose nemesis was white" , "Melville's whale chaser" , "Moby Dick's pursuer" , "Captain hunting the whale Moby-Dick" .)