Most Memorable Last Lines in Science Fiction Literature?

My apologies if this has been discussed before.

The “Science Fiction Short Story ID Help” thread
https://boards.straightdope.com/sdmb/showthread.php?t=878191
reminded me of some favorite S-F stories where the very last line of the story or novel had a strong emotional impact and gave you serious chills or knocked you flat on your arse.

My three favorites are from what for me is the classic era, 1950s-1970s, and all from one of the very best writers ever, Arthur C. Clarke. The post that brought the memories back includes one of them,

The Nine Billion Names Of God
My second shiver-inducer by ACC -
A Walk In The Dark
And at the very top of my list and probably my absolute favorite S-F short story - The Star
Without quoting the last line and spoiling the surprise for anyone who hasn’t read them yet, what S-F stories do you think have the most unforgettable last lines in S-F literature? Please share your favorites and their authors!

Isaac Asimov - The Last Question (short story)

James Tiptree, Jr.: “The Screwfly Solution.”

“The Sound of Thunder”

The only one that is coming to mind for me is from The Gentle Seduction by Marc Stiegler.

I don’t remember if it was precisely the last line, but the ending of Clarke’s “Hatred” had an even stronger impact than “The Nine Billion Names of God”.

Isaac Asimov - Nightfall
Daniel Keyes - Flowers for Algernon
Mack Reynolds - Compounded Interest
Robert Heinlein - All You Zombies
William Tenn - Unto the Fourth Generation

Fred Pohl - Day Million
Arthur C. Clarke - Love That Universe

To me, this is perhaps the most memorable final line in any story or book I’ve read.

Along with Nineteen-Eighty-Four.

“I have no mouth. And I must scream.”

I have no idea if the famous last lines in these were actually the last ones, but they were near the end, and when you read the titles, I think you’ll know what Iines i meant.

To Serve Man
It’s A Good Life.
All The Time in The World

(The Twilight Zone was great for this sort of thing, wasn’t it?)

For Larry Niven stories, the endings of Protector and The Subject Is Closed, were really moving for me.

The ending of Watts’s The Things, is certainty jarring. http://clarkesworldmagazine.com/watts_01_10/

Not unexpected given the viewpoint, but still.

Harlan Ellison - “Croatoan”
Richard Matheson - “I Am Legend”

Damn, the second post… ninja’ed before I even knew of this thread.

So I’ll go with Asimov’s “Nightfall”… the original 1941 “novelette”, NOT the later novel (with Robert Silverberg, 1990).

And Bradbury’s “All Summer in a Day”.

I look back on my Junior High years (none of that pansyass “middle school” for us), and I was so enraptured with SF short stories. I devoured every anthology and collection of them.

I still have so much respect for the ability to tell a tale succinctly, and moreso when it packs an emotional punch.

The punchiest was Light of Other Days by Bob Shaw.

Thirty years later, a friend gave a Short Story Party, where everyone read their favorite. This was still mine. Imagine this tale read around a fireplace during a blizzard. And after the last line, silence.
Googling it brings up some free pdfs, a .doc file, and an audio version on YouTube.

Isaac Asimov - All the troubles of the World.

Stephen King- The Jaunt (short story).

Most of the ones I thought of have been posted already.

I’ve always remembered the last line of Fritz Leiber’s “Gonna Roll the Bones,” even though I don’t remember much else about the story.

Nightfall, maybe.

Technically two lines, but…

Harlan Ellison, On the Slab

Fredric Brown’s Answer definitely belongs in this thread.

After the multiplanetary alien race finishes hooking up all their computers into a single supercomputer in order to ask it the Ultimate Question, the final lines go something like this:
“Is there a God?”

“Yes, now there is.”

A bolt of lightning fused the switch shut.