It's a cupboard spider (Steatoda grossa), one of the false widow species.
They largely stay hidden, preferring quieter, darker places. I mostly see wandering males, on the hunt for a mate.
Their behaviour (shy, docile) means that we are unlikely to clash, but they have been implicated in bites. It is not dangerous, but I wouldn't want to put a bite to the test. I just remove any from the bedroom/bathroom, I let them be elsewhere. If you're worried about potential bites to your children, put it outside.
Ok dokey - thank you! He/She is tiny and not aggressive at all, I was wondering why all my cockroaches were randomly dying off (I have feeder roaches for my reptiles) and my son found this in one of the egg crates in there. I might just put it outside anyway - mainly because my kids love animals and will probably harrass it into biting them.