I tend to stubbornly use creature to refer to any living person or animate thing (including mythological and spiritual beings). I suppose that makes me prejudiced against plants and fungi, but haven't heard any complaints from them. Supposedly an archaic form, but nowadays if someone were to call me archaic, I'd take it as a compliment. 
I also would consider that a compliment, and I would use "creature" in a similar way, although I might be inclined to include plants or fungi in the description, which definitely constitutes archaic usage of the word. My favorite archaic word of this category is "beastie", which I especially like when applied to small creatures, particularly ones too small to see with the naked eye.
