In addition to Gaige the Mechromancer, Gearbox has revealed that the sixth character, Krieg the Psycho Bandit, will release on May 14th.
Similar to the already released Mechromancer class, Krieg is not part of the Season Pass and will run you $9.99 to play as him. While this might seem steep, Krieg is a completely implemented character (like the Mechromancer) and offers players a chance to play as a more dedicated melee class. As you might expect, his high risk and high reward play style might not appeal to everyone, but will without a doubt change the standard Borderlands 2 formula thus far.