This question resolves YES if any space agency/company successfully changes the trajectory of an asteroid, comet, or other natural object in space so as to avoid it impacting a much larger body.
In order to qualify, the deflected object must have had a mass of at least 10^7 kilograms, the body it would otherwise have hit must have a mass of at least 10^19 kilograms, and the counterfactual impact must have been within 50 years of the deflection. The reported probability of impact before the deflection must have been at least 95%, and the reported probability of impact after the deflection must be no greater than 5%.
Another method of mitigating the damage dealt by the impactor, such as slowing it down or shattering it, also qualifies if it meets one or both of these criteria:
The total amount of energy delivered by the impactor was reduced by at least 90%.
No piece of at least 10% of the impactor's original mass makes impact, and no two pieces of at least 3% of its original mass impact within 100km of each other.
@LivInTheLookingGlass Correct. Dimorphos wasn't going to hit anything.
For anyone who doesn't know what this is a reference to:
https://en.wikipedia.org/wiki/Double_Asteroid_Redirection_Test