Figures like Tolkien and Lewis were part of a circle at Oxford known as the Inklings. The group formed around Tolkien in 1926 with the intent of reading sagas and myths in Icelandic. Lewis started out as a staunch atheist, and was converted to Catholicism partly through the efforts of Tolkien.
Fantasy is dangerous. The genre has its share of royalists, reactionaries, and racists. Tolkien and Lewis, who taught together at Oxford, were devout Catholics. Writers of the Left sometimes dismiss the genre as ideologically suspect, preferring science fiction in its stead. But no such distinction holds. Science fiction writers of the Left have written works of fantasy, and rightwing fantasists like C.S. Lewis wrote works of science fiction, like the latter’s WWII-era Space Trilogy: Out of the Silent Planet (1938), Perelandra (1943), and That Hideous Strength (1945). Each genre remains anyone’s game.