Doctor Aloysius James Animo, temporarily known as D'Void in the Null Void is major recurring antagonist of the Ben 10 franchise. He was once a promising researcher in veterinary science. His career was cut short when it was discovered that he was performing twisted genetic experiments on animals. He had hoped that his research would win him the Verties Award, which is an award in veterinary science. Because of the nature of his research, he lost the award to another doctor, named Kelly. This drove him mad, and he dropped off the map for five years until he could perfect his research. In the episode "Washington B.C", he finally finishes his work. For some reason, his skin is currently yellowish-green. A picture of him on Gwen's computer shows that he had normal skin in the past.
By using the Transmodulator, a device of his own design, Animo can mutate animals into giant versions of themselves. The second phase of his work involves reanimating dead cells, literally bringing dead animals back to life. All of this is in pursuit of the award which he had lost. His quest ends in failure, since Ben was there to stop him, reversing the effects of his Transmodulator by damaging it. He is arrested in that episode.
He appears again in the episode "Dr. Animo and the Mutant Ray", where he creates a much larger version of the Transmodulator using the broken-off faceplate of the Omnitrix. This version mutates living creatures with alien DNA, creating odd mixtures of alien and terrestrial creatures, such as a "Heatbat". Before he can complete his plans to use a satellite to shoot the ray all over the world, Ben stops him with Gwen's help. Since his mutants were never shown being cured, it is possible that they are still around. For some reason, his trademark giant frog is also present, though he may have simply re-mutated it sometime after his original defeat. How and when he escaped is unknown.
In "Ben 10,000", Animo is still alive, though his head is the only part of him that remains. However, it controls a unique apparatus that allows him to attach himself onto animals specially reformatted with a device (in this case, an albino gorilla) and control them. He was the one responsible for creating Exo-Skull and reviving Vilgax. He is defeated by both Gwen and her future self, Gwendolyn, as well as a cybernetically-enhanced Grandpa Max.
The animals he has mutated or reanimated include a mammoth, a Tyrannosaurus Rex, a bat, a cockatoo, a hamster, a rhino, a seagull, a squid, a hornet, and his trademark frog. Vilgax could be counted in as one of the creatures since Animo reanimated him. The same goes for Grandpa Max in "Dr. Animo and the Mutant Ray", when Animo turned him into a slug-like creature.
In "Divided We Stand", it is revealed that his first name is Aloysius. He escapes what seems to be Alcatraz Island on a mutant seagull and captures one of Ben's Dittos to access the DNA stored in his Omnitrix. He creates an army of self-replicating Lepidopterran mutants, but they are destroyed and he is captured again. Afterwards, Max deletes all of his computer files, preventing him from using any more Omnitrix DNA in his experiments if he escapes again.
He also appears in "Ben 10:Secret of the Omnitrix", but only as the instigator of the main plot. In it he tries to create a DNA bomb that was designed to devolve all life on Earth. He is defeated and the bomb is disabled, but a stray burst of energy is still emitted by it. Ben's Omnitrix absorbs the energy, causing it to start a self-destruct sequence and therefore beginning the plot.
He makes a brief appearance at the end of Goodbye and Good Riddance, wearing an ape-like exo-suit, and leading a group of animal mutants towards Ben's school.
Animo appears in Ben 10: Protector of Earth as the main antagonist of the South East. He battles in a robotic gorilla suit. He kidnaps Gwen at the South East. After Ben defeats Clancy, Animo's agent, he learns Animo and Gwen are at Oil Refinery. When at Oil Refinery, it is revealed that Animo as tied Gwen up to lure Ben into a trap. Ben fights Animo and saves Gwen (Thought he doesn't untie her).