There are a number of unusual folks that one might encounter, beyond the world as humans know it or just in the right coffee shop.Demons - They're more literal personal demons; not fallen angels. Demons are not nice but they are lawful, and some of the biggest problems in Wapsi Square have come when demons try to bend the rules. The Demon Realm was an accessable place but not one hospitable to human life; it exists outside of Earth's linear time, as do the demons themselves. Now that the Calendar Machine is fixed the Demon Realm is believed to be sealed off from Earth, preventing any physical travel. Not all demons are interchangable, and there are some anomalies; Shelly's companion and Tina are both unique demon-derived entities. Tina knows more about demons than anyone else in Minneapolis, but asking her carries the danger that she might actually tell you what you need to hear.
Gods and Elder Gods are mentioned, but mostly absent. Several of the older supernatural characters have gotten into myth as gods, but most of them are known to be something else - even if the difference is a bit unclear sometimes. The World Grid is supposed to keep Titans and Elder Gods away from Earth, and is apparently still doing a good job.
Golems - Postmortal magical creatures, clay dolls animated by Glyph spells and holding formerly living souls; only five are known: the three Golem Girls (Brandi, Bud, and Jin), Mayahuel, and Tepoz. See the linked page for more details.
Sphinxes may be met when you leave the mundane world, specifically apotropaic sphinxes: guardians that turn away evil. The phrase 'turn away' is a euphemism; for centuries the best tactic they had against demons was to kill the infested humans. That sort of thing gets you a reputation. As Tina once said, "Apotropaic sphinxes are who keep demons from shredding souls." Phix is the best known, and usually found in the Bibliothiki.
Titans It's unclear what Titans actually do, but they're long lived extra-dimensional humanoids. A few are known to be on Earth now - primarily Bia and Epimethius - but most are elsewhere and kept out by the World Grid. Charon is an associate of Bia; he and his daughter Tsillah may be Titans as well.
Vampires are undead blood-drinking animated corpses, substantially as common mythology has them. They're about as popular as any other dead bodies, and the sequence of events leading to the creation of a vampire is unpleasant. Fortunately their appetite for blood is limited; they rarely pose a danger to the public. Only two have come up so far, FBI agents Lily Pratt and Suzy McBride.
Others There are some people around who don't fall into well known categories, being unique or just unexplained. Tsillah, for example, although she and her father Charon might be Titans. Likewise, Atsali is a siren who goes to school with two were-bears, Euryale and her sister are medusas, and Nudge is a smartass. Stinky the giant squid has apparently been around a long time and understands English; what's with that?Werewolves exist but we haven't seen one yet; Justin just mentioned that one of his ex-girlfriends was one. We've seen a minotaur using the Bibliothiki. There are two satyrs working in a local coffee shop.