Similar to [@The Harbinger of Ferocity] I would have to say that some of the more simple creatures with maybe one single special ability are definitely a great way to spice up an RP. I am pretty fond of Blink Dogs, Corallax, and Grimalkins from D&D. I do not like campaigns that are super heavy in combat. My RPs tend to have a lot of fluff and politics and character interaction. Nothing freaks my players out more than having some random animal keep reappearing throughout the RP for no obvious reason.