The Godfather
The Good, the Bad, and the Ugly
Dances with Wolves
Trainspotting
Blade Runner
The Usual Suspects
Gone with the Wind
The Bridge on the River Kwai
The Man Who Shot Liberty Valance
The Diving Bell & the Butterfly
Nuovo Cinema Paradiso
Dancer in the Dark
Primal Fear
Crouching Tiger, Hidden Dragon
There Will Be Blood
The Thing
Snow Falling on Cedars
Citizen Kane
The Searchers
The 400 Blows
Do the Right Thing
All Quiet on the Western Front (1930)
It's a Wonderful Life
Bicycle Thieves
City Lights
Those are movies that come to mind when I think about perfect endings. Another, one of the greatest endings in film history, but a controversial one, as deeply hated by more than those who love it, probably, is No Country for Old Men. It reminds me of the way The Sopranos divides people. I remember the latter jolted me when I first watched it, I felt cheated, unfinished, but then...when I accepted what the ending was conveying, that it really wasn't ambigous, I realized leaving me with the feeling of that is precisely what made it so great.
Although I hold perhaps no ending in higher regard than I do the final episode of the HBO series The Leftovers. If you've never watched the show, that's a big ask, in terms of investment, but I'd urge you not to read anything about it. If the show is for you, you'll know by the end of the first episode. You'll be intrigued. You'll be helplessly pulled by the question of the show's central mystery. Never before have I known a work of art to lean so heavily on a mystery like this, cliffhanger after cliffhanger, and manage to deliver a satisfying conclusion. The Leftovers did, and even more. It's astonishing.