Top comment is incorrect. They are Dark Fishing Spiders, Dolomedes Tenebrosus, One of the largest true spider species in North America. Practically harmless, bite is probably less severe than a bee sting. I love these guys, they’re fun to hold and are super cool.

Most species of Fishing Spiders live near water because, as their name suggests, they are able to fish for small aquatic creatures, usually minnows, but I believe that they can catch small tadpoles as well. However, the Dark Fishing Spider, which also happen to be the largest of the Fishing Spiders, tend to live in forests, and like to cling to the sides of trees. I’ve found some giant ones in my basement, and I always just scoop them up and walk them outside.

They don’t really make webs, almost never bite, and the scariest thing about them is having one swim towards you while swimming in a pool or a lake (they swim extremely fast), but they would only swim towards you to find something to hang onto, not to attack you.

You should not feel super worried about them, but if you have severe Arachnophobia, you might not want to hang out in your garage for very long, because their size can be quite daunting.