What is the most significant "Performance of a Lifetime in the Role of a Lifetime"?

Tonight I again watched my BD of the classic One Flew Over the Cuckoo's Nest. I once again was blown away by Louise Fletcher's great performance as Nurse Ratched and, also once again, thought it was the most significant "Performance of a Lifetime in the Role of a Lifetime" I could recall. Unsurprisingly, Fletcher won the Best Actress Oscar for her performance

Let me make clear what I mean by the Performance of a Lifetime in the Role of a Lifetime. In order to qualify, the performance of a lifetime in the role of a lifetime must have, deservedly, won the performer an Oscar but the performer has never again turned in a performance that has come close to matching the Oscar winning one, much less garnered another Oscar nomination.

The only other performances and performers I can think of that have come close to fitting the definition I have given were those of Kevin Kline in A Fish Called Wanda (Best Supporting Actor 1989) and Mira Sorvino in Mighty Aphrodite (Best Supporting Actress 1996).

I have not included any of the great performances turned in by great actors who also had other great performances, for example Jack Nicholson's Oscar winning performance as Randall McMurphy in One Flew Over the Cuckoo's nest. That film marked Nicholson's 5th(!) Oscar nomination and he has gone on to several more nominations and two more wins since then.

Would be interested to learn what performances of a lifetime roles of a lifetime you guys think should be added to my lineup, or be removed from it.

There is an argument to be made for Including Al Pacino's wonderful performances in The Godfather I and II on the Performance of a Lifetime in The Role of a Lifetime list. I decided not to include Pacino, though, because he did later win an Oscar, for Scent of a Woman, and has been nominated on seven other occasions. Thus, I thought that Pacino had done and been recognized for too much wonderful work over too many years to be thought of as a one hit wonder.

My college student grandson who is a fellow movie nerd, dropped by for a few minutes this morning. When I told him about this thread, he nominated Frances McDormand's Oscar winning performance in Fargo. I agree that McDormand's performance in Fargo was one for the ages but she has received three other Oscar nominations, so probably doesn't qualify under the criteria I spelled out.

Similarly to McDormand, I don't think that any of the actors mentioned above who have multiple Oscar nominations qualify. Oddly, although I would disqualify Sigourney Weaver for that reason, I would include the actress who beat her for the Oscar in 1987, Marlee Maltin for her Oscar winning performance in Children of A Lesser God. What could have been more wonderful and less likely to be repeated than a luminous performance by a skilled deaf actress playing a deaf character? If I had thought of her, I would have included Maltin in my first post.

Thanks for the feedback, guys, you have made this thread as much fun as I had hoped it would be. Thanks also to Kilgore for mentioning Charlize Theron's performance in Monster. Despite how depressing the film is, I want to watch Theron's performance again. I will be recording it from Universal HD tomorrow and will watch it again.

In the words of Christoph Waltz's immortal line from Inglourious Basterds, "That's a Bingo!" F. Murray Abraham's luminous, Oscar winning performance as Salieri in Amadeus was exactly the sort of thing I had in mind. Abraham never had a performance before Amadeus and certainly hasn't had one since that came close to matching what he did in Amadeus.

Let me add my low opinion of Roberto Benigni's talent. I thought his performance in Life Is Beautiful was perhaps the worst among the Oscar nominees that year. Benigni was better than Tom Hanks in Saving Private Ryan or Nick Nolte in Affliction? Puhleeze! Some years the Academy makes weird choices and that was one of those years. Benigni won though, so I suppose he deserved it in the eyes of some. Thus, I must concede that Benigni certainly belongs on the list. Still, I hate, hate, hate it.

I also agree that Ernest Borgnine's performance in Marty and Cliff Robertson's in Charly belong on the list, too. Charly was a lovely film. It was based on a moving short story entitled Flowers For Algernon, by Daniel Keyes, which the author later rewrote as a novel. I read and loved the novel when it was a best seller in the '60s and thought the film was a worthy successor to the book.

I thought your suggestion of Benigni was perfectly appropriate. Although I never have had much regard for Benigni's talent, until I saw the posts in this thread also expressing dislike of the guy, I would have thought more people agreed with your point of view than mine. Go figure.

Because of other posts to this thread, I watched my Amadeus BD tonight because I wanted to see F. Murray Abraham's performance as Salieri again. Wow, just wow! If there ever has been a clearer example of the performance of a lifetime in the role of a lifetime than Abraham's in Amadeus, I don't know what it might be. Sometimes I tend to overlook Milos Forman's genius but my recent reviewings of both One Flew Over the Cuckoo's Nest and Amadeus were vivid reminders of the man's talent.