https://en.wikipedia.org/wiki/The_Left_Hand_of_Darkness
https://en.wikipedia.org/wiki/City_of_Illusions
https://en.wikipedia.org/wiki/Ursula_K._Le_Guin
Left hand of darkness is a classic. City of Illusions is also great.
I don't like fantasy as a rule but I recommend her sci-fi book The Lathe of Heaven which is a self admitted attempt to write a Phillip Dick book