The misuse of renown and renowned is a common error that makes me cringe.
Example of misuse: “was made into an award-winning TV series starring the renown actor Ian McKellan.”
Renown is a noun meaning fame or high repute, as in "an author of great renown." The adjective, meaning well-known or famous, is renowned. The renowned author . . .
If you can substitute fame, the word is renown. If you can substitute famous, the word is renowned.
Ellis, feeling curmudgeonly