Uva

Uva, the insect Greeed, is one of the five Greeed and a major antagonist in Kamen Rider OOO.

Past
Uva was one of the five Greeed created by the first OOO, a European monarch. After the King stole their Core Medals, Uva teamed up with the other Greeed to retrieve their Core Medals and defeat the King, only for Ankh to betray them to the King, who promptly betrayed Ankh and sealed the Greeed along with Ankh's right arm.

Present
800 years later, Uva and the other Greeed were released and began attacking humans to feed off of their desires and become complete. Uva suffered several defeats from the current OOO, Eiji Hino, and lost several of his medals to Ankh, who had allied with Eiji.

After Kazari's experiments resulted in the deaths of Mezool and Gamel, Uva began looking for a way to revive them and succeeded after seeding people with a Waste Yummy and producing a massive amount of Core Medals to increase his own power. However, Mezool later betrays Uva to side with Kazari, Maki and Ankh (Lost), and they destroy Uva, leaving only his Kuwagata Medal. However, Uva's essence remained in the medal and stated that "it will not end here."

Uva was later revived and joined up with Dr. Maki and the rest of the Greeed to get their medals back. After Ankh defects back to Eiji's side, Dr. Maki gives Uva back his final Batta Medal so he can assume his complete form. Now complete, Uva beats down both Birth and Birth Prototype, and OOO Putotyra and Eiji in his Greeed form.

After beating down the Births some more, Eiji returns and uses the King's Core Medals to assume the True Tatoba Combo and easily defeats Uva. With Uva dead, Maki adds the Core Medals he stole from the other Greeed into him, preserving his life as a result.

Uva attempts to continue the fight, but Maki adds more and more Core Medals, causing Uva to overload. Uva flees and pleads for help only for his body to dissolve and become the Medal Vessel. After the Medal Vessel is destroyed, Uva's Core Medals are all sucked into the black hole that emerged from the Kyouryu Greeed's body.