This beetle just looked like it must be an escaped pet, or hitched a ride on someone who just came back from a tropical vacation or field work. It was huge, and look at those horns! I did a little Googling, and found out that the reddish-brown stag beetle (yes, that is its name, and it is very descriptive) is native to the Eastern U.S. and Canada! They live in deciduous forests and nearby areas, and breed in decaying logs and stumps (I didn't think I had any of these in my yard, hence I was even more surprised). Larvae live for two years in decaying wood, exist as a pupae in the soil, and then become adults like this one. One reason I saw it at night is that it is attracted to lights at night!
If you thought they must use those horns for defense, you are right. Male staghorn beetles fight for mates with their mandibles, so those things that look like horns are really just mouthparts that tear, cut, crush and chew.
Here's a fun fact: In Japan, beetle enthusiasts will raise stag beetles and stage fights between the males!
Maybe if you are lucky, you will see one on your porch at night, too.