14. Mikhail Youzhny
Youzhny was an immensely talented tennis player in his heyday, but also a constant underachiever. The Russian star always fell short of winning a Grand Slam but had victories over great players like Rafa Nadal and Novak Djokovic. However, consistency was always his downfall. Well, almost always. He was occasionally his own worst enemy as he had a penchant for hitting himself on the head with his racket during tantrums.

In 2008, in Miami, he actually drew blood from the stupid action. That should have taught him a lesson, but it obviously didn’t because he did the same thing again in 2015. Only this time, at the French Open, he retired after suffering headaches from banging himself on the head. During other tantrums, he destroyed his own racket too. Youzhny was quite a character.