An insidious weapon born from terrorists and adopted by the military
A highly banned and controversial substance in the Cosmic Era
One of the strangest weapons deployed by Z'pl'rt the Mad
Admirals, I present to you the future of space warfare! No longer will you need to waste billions of credits on costly space battles, and millions of lives on planetary warfare with hostile cultures. For only a fraction of the cost of a heavy cruiser, I present you with a weapon capable of eliminating an entire solar system. "I present the Star Hammer!"
(A powerful and deviously simple weapon to make space warfare in any sci-fi game forever changed)
There is a person who has a well-known reputation, probably involving something illegal. But this person is either very clever and crafty, or really like his or her privacy, for no one knows who this person actually is. As an added twist, perhaps this person is of an age that would noramlly be wildly inappropriate (say, a child is a much-feared bandit) or maybe not the expected gender or even race.