Ben 10 Omni-Kix Armor Diamondhead used figure (Loose)

Ben 10 is a 51-episode American animated series created by Duncan Rouleau, Joe Casey, Joe Kelly and Steven T. Seagle. Seagle, originally aired between December 27, 2005 and April 15, 2008 on Cartoon Network in the United States. The series features the exploits of a 10-year-old boy named Ben Tennyson, aided by an object strapped to his wrist called Omnitrix that transforms him into a variety of monsters. The last three episodes were combined into a TV movie called Le Secret de l'Omnitrix.

Ben Tennyson is a 10-year-old boy who dreams of becoming a hero in order to help his fellow man. On a camping trip with his smart, mature cousin Gwen and his grandfather Max, he discovers a watch-shaped object with strange powers, called Omnitrix, in a crashed space rescue capsule on Earth, which attaches itself to his wrist. 

From now on, while retaining his childlike personality, he can transform himself into ten different aliens with superhuman powers. But this strange bracelet is coveted by terrible, determined aliens, including a galactic lord named Vilgax. As a result, the boy is now faced with threats far more dangerous than mere thieves.