How do I unlock the Barbarian and Series EV in Dungeon Defenders?

The Barbarian and Series EV hero classes are currently locked to me. However, unlike with the Crystals, it does not list the requirements needed to unlock them.

What do I need to do to unlock these classes? Finish the game once, get a certain achievement, or something else? I'm currently playing the Steam version, if that matters.

Hearing the developers when they played a few rounds with TotalBiscuit they mentioned adding more content later on. I don't know how far into this video it was, or if it was in part 2. But they mentioned that PC players got a preview of things to come in the future. It made me believe that this was the case, for those additional characters.

To elaborate, TotalBiscuit specifically made comments about some characters being locked out, and that is what prompted them to say something with regards to PC players getting to see a little bit of what's coming in the future.

These characters are now available as two separate pieces of paid DLC.