My old, old, old house, two field mice. No idea why, I had a cat. Gor one out, the other was chased to death.
My old house, a bat. Absolutely no idea how, I came home to it after work.
Current house, field mice (repeatedly and a bit fed up with catching them and driving them miles away to set them free). Ants, woodlice, spiders galore (one currently setting up base camp in my downstairs loo after I evicted two on Tuesday) wasps living in the wall, ladybirds nesting, beetles, moths and ginny spinners are regulars at this time of year.
I have aways lived on the outskirts of countryside, and as such has had to share a home with all sorts.