Rubeus Hagrid kicked Gilderoy Lockhart in the nuts.
Witnesses all confirmed that this incident occurred when the current Defense Against the Dark Arts teacher approached the school groundskeeper and glibly asked if he had any 'hot monster girls' in his possession he might be inclined to part with for a suitable sum.
Several eyewitnesses also insisted that Hagrid's boot actually caught fire a moment before it connected with Lockhart's crotch, and that this combined with the staggeringly awesome power/speed behind the blow contributed to the world-famous celebrity exploding in a ball of flame. Upon being interrogated, it was revealed that Hagrid actually stood as godfather to no less than three teenage monster girls, those being a lamia, a harpy, and a centaur, and the thought of 'that slimy reptile' coming anywhere near his three precious god-babies left him so infuriated he could not be held accountable for his actions.
This revelation turned the court of public opinion decidedly in his favor, and any charges against Rubeus were summarily dismissed without prejudice. He is now the author of a very popular set of Japanese light novels dealing with the very same subject which led up to this unfortunate incident.
Hermione Granger is president of the novel's fan club at Hogwarts.