Exo-Skull

Exo-Skull is a villain created by Dr. Animo who has fought Ben 10,000 before. He is a cybernetically enhanced rhino/human hybrid, and part of a gang of human/animal hybrids. He is also one of Maltruant's henchmen.

Personality
Exo-Skull seems to be surprisingly intelligent, even though he likes to skip the fancy stuff and focus on smashing things.

Exo-Skull respects his girlfriend, Subdora's need for artistic expression and is really supportive with her. However, when she was constantly failing to get the Orb of Pooma Poonkoo, he took over control.

Exo-Skull holds a deep grudge towards Ben Tennyson.

Ben 10
In Ben 10,000, Exo-Skull mistook young Ben as XLR8 for his future self and attacked him, but was later easily defeated by the older Ben as XLR8.

Omniverse
Exo-Skull re-appeared in Special Delivery, where he was seen attending Psyphon's assembly in order to obtain the Dwarf Star.

In Fight at the Museum, Exo-Skull and Subdora are hired to steal a valuable artifact for Maltruant. Exo-Skull gives Subdora two chances to steal the artifact through her "artistic" methods. However, after she was thwarted a second time by Ben Tennyson and his associates, Exo-Skull insisted on doing things his way. He launched a devastating attack on the museum where the artifact was stored, and continued to pose a threat despite being immobilized by Gravattack. Eventually, he and Subdora escaped with their prize and met with Maltruant to deliver it.

In It's a Mad, Mad, Mad Ben World: Part 1, Exo-Skull and Subdora rob an emporium, and are confronted by Ben and Ben 23. Though they manage to escape, the Bens follow them to the warehouse where Maltruant is hiding. During their second battle, Maltruant's chrono cog is activated, and they are all transported to Mad Ben's Dimension. A short while after, they battle with the Bens once more over Maltruant's key. Both Exo-Skull and Subdora are defeated by the Clockwork/Techno-Bubble combination, but are pulled away by Maltruant after he is reunited with his key.

In Let's Do the Time War Again, Exo-Skull and Subdora attack Ben and Rook, keeping them busy while Eon steals a pair of Time Beast eggs.

In Secret of Dos Santos, he follows Ben, Rook and Kai as they enter the Temple of the Sky. After the trio discover Maltruant's main spring, Exo-Skull attacks them. He is defeated, but both he and the main spring are pulled away by Maltruant.

In The End of an Era, he infiltrates Plumber Headquarters and steals the dwarf star from Argit, using its power to demolish his Techadons. When the present day Ben and Rook are brought in to help, Whampire manages to defeat Exo-Skull by ramming into him with a Diamondhead-based helmet. Exo-Skull and Subdora are ultimately abandoned by Maltruant as he travels back to the beginning of the universe.

Powers and Abilities
Exo-Skull has enhanced strength and endurance due to his large size.

Exo-Skull can shoot energy blasts and nets out of his horn.

Exo-Skull is immune to Whampire's hypnosis.

Equipment
Exo-Skull has two jet boosters attached to his back.

Exo-Skull's armor can withstand Corruptura-based mind control.

Ben 10

 * Ben 10,000 (first appearance)

Ben 10: Omniverse

 * Special Delivery (first re-appearance; cameo)
 * Fight at the Museum
 * It's a Mad, Mad, Mad Ben World: Part 1
 * Let's Do the Time War Again 
 * Secret of Dos Santos
 * The End of an Era

Etymology
Exo-Skull's name is based on the word exoskeleton, replacing skeleton with skull.