What I did that day was meant to help the universe, but it failed horribly. Now my greatest weapon is in his hands. Oh, this may just come back to bite me; Tonto
Artemis Fowl is a young genuis, fomely (?) criminal mastermind from the world of Underhaven. A mortal, Artemis had at some point managed to obtain Celestial Bronze, and used a torpedo combining it with LEP level explosives to capture Zeus. Then he traded Zeus with Tonto, for several pounds of gold and his Ultamatrix.
He is currently not in the hero league, instead he is using the Ultamatrix to create a power generator to help rebuild Haven. It remains to be seen if he has the potential to replicate the Ultamatrix, but it remains quite possible.