I found two of these in the same room in the space of ten minutes. One slightly larger than the other but look identical otherwise. Very shiny black body. Found with loads of dead wood lice and other dead spiders. Found behind cabinets. Thank you
Tough to identify from these photos but they look like Steatodas...I'm leaning towards S. grossa (aptly called the cupbord spider), but can't rule out S. nobilis without seeing better pics.
S. grossa are a little more widespread than S. nobilis, but spend much of their time hidden away in dark corners. S. nobilis usually hangs out in its web, higher off the ground, often in plain view.
You don't mention any markings? S grossa can be all black/dark purple, sometimes with a few feint arrow head markings. S. nobilis usually has a shield/pentangle like marking, but this can fade, especially around the rear of the abdomen.
They are both false widow species, but neither are aggressive & prefer to stay out of our way. Female S. grossa can be very elusive indeed indoors, it's more usually wandering males that get spotted. They will be fine outside if you prefer to remove them. I can imagine that you might not be exactly thrilled about finding them, but it looks like they're doing a good job on the wodlice! ;-)
I remove them from my bedroom & bathroom when I find them, but I'm not so bothered in other parts of the home...I'm looking at two S. nobilis on my living room window as I type this.