This looks to be a male Steatoda nobilis, one of the false widow species.
The males wander around looking for mates & can get into some odd places.
They're not dangerous, or deadly, contrary to what the papers would have you believe...they can bite if being crushed, but are generally quite docile. That said, I do put males outside, because of their wandering habits. Females that are 'out of the way' i tend to leave be.