The Reapers will be real obvious. They're physical, "flesh and blood", in a technical sense. Their bones are as strong as steel, and their wounds heal incredibly fast.

They can run as fast as a car going 50-60 MPH at top speed, and leap 2-3 stories, and that's without a running start.

That's why taking them on during the day is safest. But never ever take one on by yourself.

They can lift a full grown person up by just using one hand with no real effort at all.