Ursula K. Le Guin
Le Guin’s first novel is a serviceable quest story that maps fantasy tropes to a science-fiction setting. It’s engaging enough, but I’d only recommend it to someone who’s already read The Left Hand of Darkness or The Dispossessed. You can see the beginnings of a lot of the themes she explores more thoroughly in later works: Colonial exploitation, proxy wars, breaking racial stereotypes, interactions between cultures.
Fun fact: Le Guin invented the word ansible for this book.