The Space Children

"Slowly... and with horror the parents realized THEIR CHILDREN WERE THE SLAVES OF "THE THING" FROM OUTER SPACE!"

—Movie Tagline

The Space Children, a 1958 sci-fi film by director Jack Arnold.

Electrical engineer Dave Brewster and his family relocate to a coastal trailer park so that he can join the team working on the Thunderer, the latest and greatest of ICBMs and the one which will hopefully settle this pesky arms race once and for all. But the Brewster kids hear a strange sound no adult can detect, and see an eerie light in the sky. Once they arrive at their new home they are lured to a coastal cave where they, and the children of the other scientists, are introduced to a pulsating, glowing blob, which telepathically communicates with them.

Oldest child Bud Brewster acts as the ringleader as the children become servants to Azathoth's little cousin, which is a relatively benign fate compared to what happens to adults who discover the creature - Dave Brewster is struck mute or knocked out whenever he tries to tell someone else about it, another scientist gets a short-term memory wipe, and a third fellow is killed though he was an unlikable, abusive drunkard, so nobody really minds.

But that isn't the extent of the blob's powers - soon the military base housing the Thunderer suffers a string of inexplicable accidents, each occurring near a creepy smiling child, culminating in the rocket's test launch resulting in spectacular, fiery disappointment. The military rushes to take down the star-spawn, but the children form a human wall and allow the blob to ascend back into the heavens. Finally free of its influence, Bud explains that all over the planet, other children have done as they did, sabotaging the nukes and doomsday devices of the world's nations. In awe, Mrs. Brewster remarks that "the world is having a second chance," and the movie closes on a Bible quote: "Verily, I say unto you... except ye become as little children, ye shall not enter into the kingdom of heaven." (St. Matthew, Ch 18, v. 3)

...which glosses over the geopolitical ramifications of this sudden shift in the balance of power with confusing theology. So it's a movie sort of similar to The Day the Earth Stood Still, just, you know, not as good.

And no, The Space Children don't grow up into the Teenagers from Outer Space.

It appeared in this episode of Mystery Science Theatre 3000.

Tropes used in The Space Children include:

Abusive Parent: Joe, so much.

Joe: Come back here! I'll break your neck!

Adults Are Useless: ...so it's up to the children (with an assist by a lump of silly putty) to save the world.
An Aesop: Nuclear weapons are bad, 'mkay? So you should, I dunno, get rid of them or something?
- Space Whale Aesop: Disarm or a blob from outer space will enslave your children and do it for you?
The Alcoholic: Joe can't even chase down his stepson, he's weaving and staggering so bad.
And There Was Much Rejoicing: Once Joe gets mind-fragged by the blob, even the other characters admit they won't miss him.
Asshole Victim: Joe. See above.
Children Are Special: They're the only ones the Blob bothers to communicate with.
Covers Always Lie: The poster in the Trope image. As you might guess, that never happened. Of course, being the '50's, the poster was probably printed before the script was even written.
Creepy Child: Serenely grinning children act as conduits for the blob's telekinetic powers, letting them stare at locks until they break or make trucks swerve off course with a creepy stare.
Domestic Abuser: Joe again. He's probably the only character the Blob From Heaven is justified in killing, and the rest of the cast would thank it for doing so.
Eldritch Abomination: The Blob from Heaven is a big glowing gob of protoplasm.
Fan Disservice: Jackie Coogan's outfits. To quote Mike, "the producers had the very strange idea that Jackie Coogan was hot." The film was going for a creepy atmosphere, and it worked; once wardrobe decided to dress Coogan in little shorty-shorts, the rest of the crew could have knocked off early.

Servo: It's Uncle Fester in shorts!
( Coogan swings his leg over a bench to sit down)
All: Aaah!

General Ripper: Completely averted. Col. Manley is a pretty level-headed guy who has a kid of his own. He's not even that upset when the Thunderer Project goes ker-flooey at the end. It's Jackie Coogan's civilian character who wants to Kill'Em All.
Giant Space Blob From Nowhere: What exactly is it, where did it come from and where the hell does it get off telling us what to do with our weapons? Y'know what, blob? You can just bite us! You have no right to-gah! What are you-aaagh! HAHAHA. DISREGARD THAT. THE BLOB IS AWESOME. GO TEAM BLOB. YAY.
Huge Schoolboy: One of the "children" following Bud around looks a little too pubescent to play with that age group.
Invisible to Normals: While they're doing the blob's bidding, the Space Children can walk right by security checkpoints.
Kill Sat: The Thunderer launches an H-Bomb to a geosynchronous orbit over a target city, just waiting for the order to drop the metaphorical hammer.
Mind Rape: Coogan's character gets a minor dose after following his daughter to the blob.
Moral Event Horizon: Ostensibly the blob crosses this line when it kills Joe.. But then no-one cares.
Mundane Made Awesome: Every shot of the Thunderer is accompanied by a majestic fanfare, even though it's visually quite unimpressive.
Non-Indicative Name: The eponymous children are not from space, nor do they go into space.
Nuke'Em: Hank's idea for how to end the Cold War.

Mrs. Brewster: ...when is it going to end? Year after year of racing, racing trying to find something bigger and better to blow ourselves off the planet. When they ask me these questions, what do I tell them?
Hank Johnson: You just say to 'em that down there stands the Thunderer, and what are we waiting for?!
Servo: Hank would kill everyone if you let him.

Soundtrack Dissonance: When the truck drivers lose control of their vehicle, causing it to weave back and forth and eventually careen off the road, the musical accompaniment is placid and ethereal.
Swiss Cheese Security: The base housing the Thunderer is protected by a chain-link fence with exposed locks, a security kiosk with a wooden retractable barrier, and some signs. Even when they aren't under the blob's protection, the kids are able to run right up to it to gawk at the missile.
Why Did It Have To Be Sand?: It ruins everything you know. Everything.
The World Is Not Ready: ...to disarm itself, so the Blob From On High shows up to do it for us.