Board Thread:Series Discussion/@comment-10227025-20130530152404/@comment-3235402-20130530195731

Ben 10 Planet's forum might have been a better place to ask this, but as far as this site is concerned, this belongs in Off-Topic. :P

Anyway, that's Bullfrag, the Incursean alien from The Frogs of War: Part 2. In the opening, though, he seems to have had his clothes redesigned to look more like an Omnitrix alien.