Everyone knows that X-COM accidentally shot Santa down in '99... No, really we did...
It was December 24, 2305 hours when we picked up a tiny unidetified object flying south from the north pole. Reacting with practiced fluidity we dispatched a firestorm to intercept.
Not until my brother (who was looking over my shoulder) said something that we realised our mistake, but it was too late, christmas had to be cancelled.

A recovery team was dispatched on one of our old Rangers but the craft's occupant had been killed on impact.
(true story, which makes it all the funnier

)