Diamondhead

Diamondhead is a Petrosapien alien from the planet Petropia.

Ben first transformed into Diamondhead in the first episode, And Then There Were 10.

Abilities
Diamondhead's body is composed of an extremely dense and durable organic crystal, making him nearly invulnerable.

Diamondhead can manipulate the atomic structure of his diamond physiology at will, allowing him to create crude crystal weapons from any part his body on demand or fire crystal shards from his hands. In certain ways, he can reshape his projectiles into certain shapes. He can even control those that are not connected to his body. This same ability also allows him to regenerate to an extent, such as regrowing lost limbs. In addition to growing crystal from himself, Diamondhead can growcrystal over other objects. In the episode, Vengeance of Vilgax: Part 2, Ben as Diamondhead, seems to levitate three pillars of crystal that he controls to aim toward Vilgax, defeating him. Lasers and other similar weapons are useless against Diamondhead, as his crystal body acts as a prism, refracting the beams. He also has proved strong enough to easily beat Kevin, defeat Vilgax, and smash apart various objects with relative ease(an example of this is when he mutilated a semi truck just by sneezing). The one drawback to Diamondhead's crystal form is the crystal itself, which can shatter if exposed to sufficiently strong sonic vibrations. Though his diamond structure is durable, it can be damaged with sufficient force. While Petrosapiens can regenerate limbs, there is a limit to how much damage they can recover from.

Gwen 10
After turning into Heatblast, she then turns into Diamondhead after learning about many of the other aliens but she doesn't turn into Wildmutt after Heatblast like Ben had done in And Then There Were 10. Her fight with the giant Vilgax drone almost mirrors Ben's fight in the series premire. However, she uses her book smarts to effectively rebound the laser blast without doing more than necessary damage.

Race Against Time
Diamondhead appears as the third alien Ben transforms into in a live-action movie and fights Eon once but gets away. Ben spent his remaining time as Diamondhead in the girls' locker room.

Alien Force
Diamondhead(voiced by Dee Bradley Baker) makes an appearance in the third season premiere of Alien Force, regenerating from Chromastone's remains after Vilgax destroyed him. Diamondhead's appearance is slightly altered(but similar to his appearance in Ben 10,000), with a primarily dark blue uniform that also covers part of his head(however, all petrosapiens have this natural "costume". It wasn't seen before since Ben's clothing covered over it)and his crystal body is more blueish and dosent make the same crystal like noise when he walks anymore. In this series, his crystals can explode and he demonstrates the ability to psychokinetically control the crystal he creates.

Diamondhead's body is different in that his Omnitrix symbol is now in his chest and his eyes are now green. He also has a similar body structure to the one of Chromastone, a related species. In the episode The Secret of Chromastone all Petrosapiens have a dark purple body(in the original series we never saw that because both Ben, Tetrax and all the Petrosapiens were wearing clothes). Ben transforms into Diamondhead after Vilgax destroys Chromastone's body(seemingly killing Ben in the process, but the crystals that made up Chromastone re-constituded into Diamondhead, giving Ben access to this form once again. As Diamondhead, Ben states "You're in trouble Vilgax; I've had a lot of practice with this one.", indicating Diamondhead is one of the alien forms that he had a lot of experience with(this maybe in reference to a scene from an episode of the original series, in which a young Ben can be seen training in this form under the guidance of Grandpa Max), possibly due to it being one of his original ten alien forms. Ben proves this by using it to literally crushing Vilgax(under three giant chunks of crystal), forcing the villian to yield defeat. Ben's use of Diamondhead to defeat Vilgax is ironic since he is the one ultimately responsible for the destruction of Petropia.

Diamondhead is now once again selectable in the Omnitrix. Ben briefly transforms into Diamondhead in the episode Single-Handed after becoming trapped in the Null Void after he is dimensionally displaced from his left hand(the hand that wears the Omnitrix) by the bounty hunter Sunder. This saves Ben's girlfriend, Julie Yamamoto, from Sunder, while she is trying to protect Ben's left hand and the Omnitrix. Ben's dimensionally displaced hand protects Julie by firing Diamondhead's crystal shards. However, this causes problems for Diamondhead, as his left arm also fires shards, unintentionally destroying a rock bridge he was walking on. Diamondhead also appeared in the episode In Charms Way, fighting a hypnotized Kevin. Diamondhead also appears in The Secret of Chromastone by releasing Sugilite inside him, where he saves his home planet Petropia with the a crystal Vilgax had that can regenerate Petropia and their species. He was also used by Albedo to fight and kidnap Kevin and one of the alien forms Vilgax's army of bioids take.

Ultimate Alien
Diamondhead has yet to reappear in Ben 10: Ultimate Alien as an additional alien, but is known to reappear in his Alien force appearance due to his hologram on the ultimatrix when terraspin was scanned

Possible future
The possible future set in Ben 10,000, Diamondhead has regained predominant clothing. As well as a black-layered shirt, the Omnitrix symbol has moved to the center of his chest from the left side of his chest. His pants are now white and he has black boots, and his jaw also seems jagged.

Naming and Translations

 * Bulgarian: Диамантеният/The Diamond (One)
 * Croatian: Kristalni/ The Crystal (One)
 * Dutch: Diamantkop/Diamondhead
 * German: Stahlschadel/Steel Skull
 * Italian: Diamante/Diamond
 * Norwegian: Hardhaus
 * Polish:Diamentogłowy
 * Romanian: Cap de diamant/Diamondhead
 * Russian: Almaz/ Diamond
 * Spanish: Diamante/Diamond

Trivia

 * In the German version of the series, Diamondhead - like so many others of Ben's aliens - was for unknown reasons misnamed. In his case he was called "Stahlschädel"(Steel Skull), even though he is evidently composed of a crystalline substance.
 * In the episode Vendetta it was shown that Diamondhead absorbed Ragnarok's energy blast and redirected it like Chromastone.
 * In Vengence of Vilgax Ben, as Diamondhead, shot diamond projectiles at Vilgax, injuring him. However, in the original series the projectiles didn't have any effect.
 * It is shown that Diamondhead's transformation in Alien Force is similar to Chromastone's.
 * He is the first alien used by the Ultimatrix.(Albedo)
 * In the Brazilian version of the series he is called "Diamante" (Diamond).
 * He is one of the five aliens to appear in all three series. The other four are Upchuck, Ghostfreak, Way Big and Cannonbolt.
 * He is the 4th alien from the original series to reappear in a sequel series.
 * In the original series,Diamondhead shifts his hands to cut something but in Alien Force he doesn't shift his hands.