The Giga-Dino Plasmid aka Sean Bennett is a artificially created lifeform made from the genetic remains of several destroyed Plasmids as well as dinosaur DNA and data on Kamen Rider OOO Putotyra Form. Because he was freed prematurely as an egg and raised by Lily as her son, he has defied his creators and aided the Kamen Riders in battle after the death of Kubick.
Sean was designed by the Pra'Meths to age at an accelerated rate so he would be combat ready within a few weeks. As a result, his appearance changed as he aged.
As a baby, Sean resembled a human infant with green eyes.
As a child, Sean began mutating into his true form by his skin getting harder and more scaly, growing a tail and nubs on his back that would eventually become wings.
As a teen, Sean began growing larger and his wings and skin were fully formed. He transformed into his true adult monster form due to his rage of being born a freak and the Bat Plasmid hurting his "mother". He was stopped by Kamen Rider Nile's sorrow and love for him and the Earth Soul Legend Round purifying his body.
His corrupted adult form he briefly assumed resembled a 3-headed, four armed humanoid Hydra with each head representing a part of Putotyra form.
In the purified version of his adult stage, Sean became a giant, buff humanoid dragon-like creature with Pteradon wings on his back. His body has a T-Rex tail with a spiked Ankylosaur club tail at the end and sharp claws on his large hands and feet.
Sean has the combined abilities of several Plasmids including Iguana's strength, Gila's regeneration, Bat's flight speed and Copperhead's muscle tissue in his tail to constrict his enemies. In addition to this, he has night vision and his thick hide can withstand conventional weapon fire and electricity. In his corrupted adult form, he could fire plasma bolts and freezing blasts from his mouths. After being purified, Sean could assume a human form.
- While thinking of a name for him, Lily, Adam and the Seer mentioned several names related to stories with dragons: Peter, Berk, Shinji, Haruto, George, Ryu, and Phillip.
- He is named after Sean Connery and there are 3 allusions to this: Lily mentioning Dragonheart as a joke, his black teddy bear and his stasis tube label of Weapon-Subject #700 (007 backwards)