Emmanuelle Beart stark naked in La Belle Noiseuse
She probably hold some kind of a record for a mainstream actress in that she is completely naked for about two hours of running time.
Unfortunately, the movie also includes another two hours in which she is not naked. IMDb voters like it (7.8), but I cast a dissenting vote.
(The other reviewer mentioned in the article, “Tuna,” was my long-term collaborator on the Fun House. He has since passed.)