We had a professor at UNC, little German guy, pretty famous, named Eliel. He was the "Big Gun" in the department, but far. And also consistently voted best teacher by the undergrads, who had no idea who he was.
I never had him for a class, we didn't take that many classes anyway, but he was on my committee (of five).
He didn't nail me in my orals at least.
Orals could end badly, and often did.