The definition of a fantasyauthor is somewhat diffuse, and a matter of opinion - Jules Verne considered H.G. Wells to be a fantasy author - and there is considerable overlap with science fiction authors and horror fiction authors; however some notable part of the output of the following writers leans more to the fantasy end of the spectrum:
... left side is now a perfect square; it is the square of (x + b/(2a)). The right side can be written as a single fraction; the common denominator is 4a2. W ...