Technology that the inventor(s) intended for peaceful and/or constructive purposes is weaponized.
A well intentioned Gadgeteer Genius who creates horrifying weapons without thinking of the potential. Heavily overlaps with Reluctant Mad Scientist. Related to Misapplied Phlebotinum, although who's doing the misapplying depends on your perspective.
- In the horrifically bad movie Danger! Death Ray the scientist creates a death ray, yes a DEATH RAY, intending it to be used "for peaceful purposes only" Needless to say when MST 3 K got ahold of the film they had a field day mocking the absurdity of this concept.
- Leonard of Quirm from Discworld. Most of the time he doesn't even think of the military applications of his inventions, but even when he does, he's convinced that no one would be evil enough to use it.
- In the Star Wars Expanded Universe novel Jedi Search, Han confronts an incredibly naive Imperial weapons designer about the projects she's worked on. Projects with names like Death Star, World Devastator, and Sun Crusher. Did she really think that these would be projects with peaceful applications? Yes.
- In one of the Wiz Biz books, Wiz creates a spell that repels magical creatures for the country folk long terrorized by various monsters. To his horror, someone alters it to create a spell that kills magical creatures, and the villagers start aggressively using it on every creature in their path including neutral or friendly ones.
- In Metal Gear Solid, Otacon intended the Metal Gear he designed to be a defensive weapon, somehow not realizing that it could fire nukes.
- The inventor of the Gatling machine gun hoped it would reduce the overall size of armies by mechanizing warfare (in a strange and rather depressing inversion of the Luddite's fallacy).
- Nobel created dynamite for mining applications and realized he was being treated as an arms merchant.
- Robert Oppenheimer, and indeed many scientists on who worked on the Manhattan Project later regretted developing the atomic bomb. This may not count, though, considering that they knew they were creating a weapon that was meant to end the war.
- In The Venture Bros. pilot episode "The Terrible Secret of Turtle Bay", the Venture family travels to New York City, where Dr. Venture is presenting his newest invention to the United Nations. Dr. Venture explains his new invention, the "Oo Ray". He cheerfully melts a model city in demonstration and is completely mystified by the audience's negative reaction. The U.N. representative hosting the conference scolds Venture, who fails to see any violent applications for his gadget, and apologizes to the crowd. A general then cheers Venture up greatly by buying a hundred Oo Rays for the Army (though Dr. Venture clearly has no idea what use the Army could make of his invention).
- In one episode of Buzz Lightyear of Star Command, the LGM present a variety of new inventions. Both Buzz and the LGM dismiss the 'Quantum Trash Compacter' as having no defense applications, but Zurg later steals it and uses it to collapse their planet's sun.
Hello, Unknown Troper. You'll need to get known to lend a hand here.