Gou from Free! Iwatobi Swim Club. She doesn't like her really name because it's a boyish name so she wants to be called Kou. But one of the characters continues to call her Gou because he knows it bothers her.
Well, finally characters stopped mispronouncing his name, but it used to happen to Stephan/Kenyan from Pokémon. Ash and his vrienden usually called him "Stefen" and each time he'd respond "My name is Stephan". Pokémon breaks the fourth uithangbord a lot and Stephan broke the fourth uithangbord towards the end of "Commanding the Clubspolsion Crown" yelling at the narrator after the narrator mispronounces his name. In the picture you'll see what he usually looks like when people mispronounces his name. I understand how he feels, people mispronounce my name sometimes and I don't like it.