Fame
Sometimes, yeah, if you're successful. A lot of people know the names Watterson, Schultz, Larson, Adams, etc., but they don't know what they look like.
Cartoonists are often fairly introverted people, so the anonymity suits many of them just fine. Watterson in particular is a famous recluse; he doesn't want anyone to know where he is, so pretty much nobody does. We assume his wife does, but considering no one's heard from her either, even that much is speculation.