Early in his career, they called him "La Comète", The Comet.
In French.
Then, The Rocket came along and that stuck.
In French, he's referred to by his full name, and as "Le Rocket". Rarely Maurice "The/Le Rocket" Richard. Never as Rocket Richard.
Brother Henri is called "Le Pocket"
Jean Beliveau is invariably called "Le Grand Jean Béliveau", The Great Jean Béliveau. And invariably, INVARIABLY called Mr. by everyone.
There's a special relationship between the status of The Rocket and the status of Mr. Béliveau. Equally good, but not in the same way. Rocket is the greatest folklore hero and national hero. Mr. Beliveau is a king amongst men, and could have been premier of Québec or Canada, or governor general, or hell, he could have married Queen Elizabeth and be a great monarch. Not that Rocket couldn't have been, but Mr. Beliveau carries that vibe with him.