Revivalists be like Cuchulain Cuchulainn Cuchullain Cuchullainn Cuchulin Cuchulinn Cuchullin Cuchullinn Cuculain Cuculainn Cucullain Cucullainn Cuculinn Cucullin Cuchullan Cowchullin (seriously) Cuhoollin... basically every permutation besides the accepted Irish rendering Cรบ Chulainn ๐ญ
Fabula Celtica Podcast
Well over a century of people being annoyed about this. (Seriously, there's so many iterations I have to check in web searches... it's a bit of a nightmare!)