2K Games teased that a new Vault Hunter was coming to Borderlands 2 a few days ago. The publisher has now released a teaser trailer for that states that the debut of the new DLC will be at the PAX East panel by Gearbox on the 24th March.
The teaser warns that an experiment has been unleashed, and bandits had better beware.
Strategy Informer will be at PAX East reporting it first hand.