At first glance one might think that fantasy literature these days consists mainly of the "4 R's" J.R.R. Tolkien and George R.R. Martin. Tolkien's "Lord Of The Rings" was widely considered the genre's essential work even before a movie trilogy further boosted its popularity. George R. R. Martin's "A Song of Ice and Fire", on the other hand, only reached it's current enormous, and thoroughly deserved, level of popularity with the TV adaptation "Game Of Thrones".
These two works do indeed cover a wide spectrum of fantastical themes. Tolkien's fight against evil contrasts with Martin's political machinations, his rough humor and wickedly ironic plot twists. The common ground between these two very different authors is their passion for world-building, and this is one of the important traditions in fantasy literature shared with countless other writers. Brandon Sanderson, for example, who is not only an enthralling storyteller, but also the creator of a highly original fantasy universe. Or R. Scott Bakker and Steven Erikson, both stylistically exuberant and forceful, and thoroughly unafraid to challenge their readership. There's Robin Hobb, who populates her unusual world with complex and believable characters, or Kameron Hurley who pretty much tosses the whole rule book out of the window with her Worldbreaker saga.
There are other long-standing traditions in fantasy of course. Sword & Sorcery, to name one, largely birthed from the mind of Robert E. Howard in the hulking form of his barbarian hero Conan, was extended by C.L. Moore, Karl Edward Wagner, Fritz Leiber and Michael Moorcock, and is still being continued and reimagined in the works of authors such as Joe Abercrombie, Michael Sullivan, Anthony Ryan, Glen Cook, Andrej Sapkowski and Alex Marshall. And then of course there are a multitude of books that defy categorization: Mervyn Peake's classic Gormenghast, which has inspired countless later authors; the stylistically outstanding works of Jeff VanderMeer, Jo Walton, Neil Gaiman or Guy Gavriel Kay; the impish, sneaky, and brilliantly executed novels by K.J. Parker. And certainly also Terry Pratchett's books, renowned far beyond genre fandom and the proof that fantasy can make you laugh and think at the same time.
An old prejudice against fantasy makes it out to consist mainly of conservative feel-good escapism or adolescent dreams of powers. Hopefully the above list of authors alone will be enough to dispel this particular myth. It further loses validity if we look at the more recently published wave of works that are highly ambitious in their language, concepts and politics: N.K. Jemisin's Broken Earth trilogy takes a hard look at racism and persecution; Seth Dickinson's Baru Cormorant series dissects the techniques of imperial power, and G. Willow Wilson elegantly examines the Arabian spring in her highly entertaining novel "Alif The Unseen".
If you wish to delve deeper yet (beware the Balrog!), there's the "Virconium" sequence written by M. John Harrison, Joanna Russ' "Alyx", and Samuel R. Delany's "Nevèrÿon" series, all of which explicitly set out to deconstruct classic fantasy and pull the genre right into the twisty maze (or lofty spires, as you will) of literary theory.
And with all this we've barely scratched the surface, not even mentioned famours names such as Markus Heitz, Patrick Rothfuss, China Miéville, Trudi Caravan or Ursula K. LeGuin. Just like science fiction, fantasy is a living, breathing genre which is developing into dozens of directions simultaneously!