TOMORROW BELONGS TO ME tops my list. The best horror scene ever comes from CABARET
Number two easily goes to the greatest gunfight and showdown scene ever in RIDE THE HIGH COUNTRY
Two from "Hair". The wrong man sent to Viet Nam scene and the best character entrance ever scene with "Easy to Be Hard".
The cat scene from BREAKFAST AT TIFFANY'S. Without this scene, the movie is nothing
The lion scene at the end of TARZAN AND HIS MATE
Von Ryan running to catch the train
The final chase scene of CHARADE
The crop duster scene, do I even have to say N by NW?
Many scenes from 49TH PARALLEL, most of them in the Christian work community, ending with the execution.
The execution scene of the original RED DAWN
The log scene makes King Kong. Without the log scene, it's nothing.
The final scene of JUNGLE FIGHTERS. All characters meeting an ironic fate.
Christopher George hamming up his death in ENTER THE NINJA
Sam feeling sorry for what he knows will happen to his killer and former friend in GHOST
Gregory Peck confessing in the cathedral at the end of THE BRAVADOS
Several iconic scenes from MONTY PYTHON AND THE HOLY GRAIL, notably the black knight
Same for BLAZING SADDLES, notably the camp town ladies song
The stately NCO dance scene from FORT APACHE, when we know they are all doomed men in their last dance
The beginning scene of SEVEN MEN FROM NOW
The final duel of THE TIN STAR
Ben Johnson as Chris, sitting outside, hearing Palance as Wilson cackling while the farmers meekly begin to back down.
Beginning and final scene of D.O.A. (1950 though sometimes given 1949), and also the scene where Bigelow learns of his fate and runs the street
DESYAT NEGRITYAT when Vera thinks she is the last one, and passes by Wargrave's body
NANKYOKU MONOGATARI ending, the men finding Taro and Jiro
Many scenes from SEVEN SAMURAI, notably the scene in which Mosuke first breaks down when he realizes his home is to be sacrificed, and later when he repents of this. The movie is really more about the conflict between the dishonorable conservative elder Manzo and the more honorable liberal elder Mosuke.
The second quicksand scene of MAD MAX BEYOND THUNDERDROME
The accordion playing with feet stamping in the scene shared by Stewart, Murphy, and Duryea in NIGHT PASSAGE
A guy thing, the absolute knock out babe in her boots at the top of the stairs when the soldiers meet her in THEN THERE WERE THREE
Franco making his early boast about wiping out all those Germans at the end of THE DIRTY DOZEN
THUNDERBALL with many, three in particular. Still unbeaten as the most exciting underwater battle scene ever on film, the board room assassination of the "culprit" when we know which of the two is surely the embezzler by looking at them, and the assassination of the "little fish".
FOR YOUR EYES ONLY-We're not dead yet
THUNDERBALL with several, but notably the end when the mission is over, and XXX must fulfill her vow.
WAR OF THE WORLDS 1953 with many, notably the farm house scene. I never liked fried eggs before that, but now I love them.
THEM! Peterson saving the boys at his own peril
THEY LIVE when the hero first uses the sunglasses
UNKNOWN WORLD
when the one we think is the hero falls to his death, and the villain changes into hero.
MISSING when Jack Lemmon finally realizes he was mistaken about his government doing right.
Several from THE CAINE MUTINY, but headed by Jose Ferrer giving MacMurray a drink he didn't expect
BLACK LEGION when Bogie breaks down and confesses in the end
Shower scene from PSYCHO
The cut away scenes from mountain execution to doomed man's crying dog in SECRET AGENT
Final duel of DEATH DUEL
Final duel of FIVE DEADLY VENOMS,
when the young trainee does as told by master in combining with a venom to beat the others, ironically, they only participate as the three remaining evil venoms kill each other
NIGHTFALL with many, notably the end when the investigator in over his head and the man who came across stolen loot are in a bind against a lunatic killer who makes a game out of his assassinations.
12 TO THE MOON the drawing of lots to save Earth.
FIRST SPACESHIP ON VENUS with several, notably the final scene when the astronauts return after losing contact with Earth, and 5 of the original crew of 8 emerge from the vessel, and the fifth clangs the door shut behind him.
May think of more, but these are certainly awe inspiring ones that need mention.