A preteen boy, Tommy liked to visit the elderly Mr. Hopkins, a tinkerer whose hobby was building gadgets; although Tommy's mother objected to his spending so much time around the eccentric old man (she thought he should associate with more "cultured" people), his father saw no harm in it ("At least it keeps him away from that blamed TV set of his!").

One day, Tommy read in a newspaper that an industrial fair -- featuring all kinds of mechanical and electrical machines -- would be held in town at the end of the year. Thinking that the fair would be the perfect opportunity for Hopkins to show people how talented he was, Tommy encouraged his elderly friend to construct a big and impressive machine to exhibit.

Tommy assisted the old man in salvaging parts from junkyards and building a giant remote-controlled robot, which Tommy dubbed "Mechano". But when they took the robot to the fair to display it, a one-in-a-million-chance atomic accident turned Mechano into a self-regulating machine, and it no longer responded to the remote-control unit. As the giant robot went on a rampage of destruction, the police mobilized to destroy it, so Hopkins sent Tommy back to his workshop to retrieve a large electromagnet.

Tommy and Hopkins used the electromagnet to lead the berserk robot into a wooded area on the outskirts of the city; but coincidentally, they happened across an extraterrestrial invasion force that had just landed. As Tommy and Hopkins took shelter behind a rock, Mechano turned its attention on the invaders, who were overwhelmed by the robot's assault and forced off the planet.

But moments later, the police arrived and destroyed Mechano with their gunfire. Afterwards, Tommy asked Mr. Hopkins if they should tell the police about the alien invaders, and how Mechano had saved the whole world; but Hopkins responded that no one would ever believe them.

--Strange Tales I#86/1

A reclusive tinkerer, the elderly Hopkins (first name unrevealed) lived in a shack on the outskirts of town; he earned a living by doing odd jobs around the neighborhood.

Hopkins was often visited by young Tommy Briggs, and he impressed the boy with the gadgets that he built. One day, Tommy encouraged Hopkins to build something to display at an upcoming industrial fair, so Hopkins constructed a giant remote-controlled robot, which Tommy dubbed "Mechano".

When they took Mechano to the fair, a one-in-a-million-chance atomic accident endowed the robot with a will of its own, and it would no longer respond to the remote-control unit; subsequently, Mechano ran amok.

After Mechano demolished the exhibition building, Hopkins heroically jumped upon the robot's back and tried to halt Mechano by jamming a crowbar into its "pinion gear," but his foot slipped and he fell off. Hopkins was uninjured, and the giant robot continued its rampage. The police mobilized to hunt down and destroy the runaway robot; but Hopkins was determined to save his masterwork, so he sent Tommy to retrieve an electromagnetic device from his workshop, which he used to lure Mechano to a wooded area on the outskirts of the city.

But when an alien invasion force just happened to land in the forest at the same time, Hopkins and Tommy took shelter behind a rock and watched as Mechano fought the invaders and forced them away.

Moments later, the police arrived and destroyed Mechano with their gunfire.

As the police began to leave, Tommy asked Hopkins if they should tell them about how Mechano had driven off the alien invaders and saved the world; but Hopkins replied: "No, Tommy! People would just think we had imagined it -- because you are too young, and I -- I am too old!".

Then Hopkins philosophically proposed that in its own way, perhaps Mechano had repaid destiny for the accidental gift it had been given -- the gift of life.

--Strange Tales I#86/1

An exhibit at an industrial fair, it was accidentally activated when two workers dropped it while setting it up for display.

It subsequently fired a beam of pure energy, which hit the remote-controlled robot Mechano and caused it to run amok.

--Strange Tales I#86/1

The invasion force of an unidentified race of hostile humanoid beings, they numbered at least six; they were armed with a nuclear cannon and electron ray-guns.

Believing that Earthlings were small and weak, they landed their spaceship with the intention of conquering the planet.

But they just happened to land in a wooded area, where Tommy Briggs and Mr. Hopkins were leading the rampaging robot Mechano with an electromagnet.

Mechano smashed the invaders' nuclear cannon, and their electron rays proved to be ineffective against the giant robot, for Mechano had no nervous system.

Realizing that they were overpowered by the metallic giant, the aliens abandoned their plan of conquest, climbed back aboard their spaceship, and presumably returned to their homeworld.

(Comments: These aliens were never depicted without their helmets, so we don't know what their real faces looked like (Of course, that's assuming that those were helmets, and not their actual heads!). And considering the shape of the their word-balloons, maybe they "spoke" to each other telepathically.)

--Strange Tales I#86/1