I’ve seen lots of spiders and one time a frog got stuck there. I didn’t actually see this but I did have a snake in the basement dead in the storage area of our sump pump. I believe he came in from the garage crack b/c the only way to get in there is through the wall, which is adjacent to the garage wall. I had a neighbor who had a similar issue.

I'm not an expert on these things, so I'll defer to others with better ideas. However, if it were my house, I'd probably just squirt in some concrete caulking and call it done until it needs it again in a few years. For a wider crack, I might force in vinyl concrete patching compound or hydraulic cement.

Backer Rod and Caulk and if a wider crack just as DavidR suggests.

If I’m understanding correctly what you have on the left is the house foundation and the garage slab on the right, with the crack between them? Given that the foundation goes down 4’ or so, I find it hard to believe that an critter is going to burrow down that far to get in your basement.

But if it bothers you and as other have said, backer rod and caulk. The backer rod is a flexible foam cylinder that’s used to fill space so that you don’t use as much caulk, which will just fall into the void. Available at your home center, usually in the weather stripping section.

Thanks everyone!!