A bud and I were camped in some woods in Oklahoma. We'd been in our tents for a few minutes. I was on the phone with my wife. Suddenly, the wildest, loudest, screeching we'd ever heard commenced, seemingly from just a few feet away. Continued for a minute or two. Neither of us had ever heard anything like it before. Or since. Wildcat, Screech Owl? IDK.
Another adrenaline attack was when I poked my head out of the tent on a New Mexico mountain top to see a 'wolf' starring at me from about 20 yards away. Turned out to be a lonely, hungary, very shy German Sheppard. We shared supper and he slept at the head of my tent.
Addenda: I forgot about solo camping on an Indian Res in SD in a run down, remote park and being awakened at 2 am by gun fire from the nearby dirt road. That was scarier than the screeching animal. The firing went on for about 15 minutes. I could hear kids talking. Thankfully they never came into the park.