Not sure about widly successful, but the very influential Australian sculptor Rosalie Gascoigne didn't start any artistic endeavours until she was in her 60s. She ended up being the first Australian woman to exhibit at the Venice Biennale and her works are in all of the major Australian and NZ galleries as well as in the Met in NY

Peg Phillips was an actress on the show "Northern Exposure" in the 1990s. She did not try to become a professional actress until she retired as an account in her mid-60s. https://livingafter60.com/its-never-too-late/

I would also like to hear these. Starting later in life means you come into the game with way more experience and maturity, and a storehouse of memory and detail to draw upon. It’s very hard to fake that if you haven’t lived it.

Norman MacLean didn’t write “A River Runs through It” until he was 65. Yet, as mentioned, he worked his whole life for it. The novel is semi-autobiographical and obviously MacLean’s time spent in Montana shows. It didn’t hurt that Robert Frost was his professor and Theodor Geisel his colleague at Dartmouth.