Diamondhead

"I've had a lot of practice with this one." - Diamondhead.

Ben as Diamondhead
Diamondhead has a bulky, crystaline body with long spikes across his back. Since Ben has aged Diamondhead's appearance has also changed. Diamondhead now has the Omnitrix located on his torso with a black and white suit.

Credit
The picture in the infobox belongs to elmike9.