As you can see from the photos that accompany this blog, males sport two pronotal horns that some described as looking like the horns of a rhinoceros. The males use these horns when fighting for the opportunity to mate with females. Females lack horns. 
I’m in middle TN. Was just cleaning out my fireplace that I haven’t used for a few years. Just found one of these in there and was completely shocked by it’s size, at least 2-2.5 inches. Never seen these before. Apparently mine is a female. Neat looking critter.
Thanks for sharing your fascinating comment. That was indeed an unusual place to find one.
Mine was beside a gas fireplace
Thanks for taking the time to share your hercules beetle sighting. I guess your experience goes to show this big insect just might show up anywhere.