There's quite a lot of people who do read in my surroundings (hurray!), however, they don't all read fantasy, sci-fi and horror. I tend to read a lot of books that haven't been translated to Dutch, so lots of people don't know those authors.
Most people know Tolkien of course, whether they've read it or not; most people know that the movies have been based on a book (I hope...). All have heard of Harry Potter by J.K. Rowling, of course.
Some people know bestselling translated books like Feist (though I don't read his books...), Robin Hobb (who is very popular among the fantasy fans here in Holland), Neil Gaiman and possibly Tad Williams and George R.R. Martin.
They usually don't have a clue if I talk about authors like Jeff VanderMeer, R. Scott Bakker, Carol Berg, etc.