Dave

Dave, also known as Dr. Octavius Brine, is the main antagonist of Penguins of Madagascar. He is voiced by John Malkovich.

Role
Dave was originally an octopus that lived in the Central Park Zoo. He entertained children with his many tricks. However, when the Penguins came along they stole all of his glory and he was then transferred to another zoo. The same thing happened again and again and again. Dave then grew hateful towards penguins and plotted revenge against them. He escaped captivity and became a mad scientist and supervillain. He created a green chemical called the "Medusa Serum", which turns animals into evil, hideous monsters. He disguised himself under the alias "Dr. Octavius Brine" and kidnapped penguins from every zoo he had lived in, including Skipper, Kowalski, Rico, and Private.

Private escapes, but Dave still turns the penguins into monsters. He then releases them on a rampage in Central Park, allowing them to terrorize the citizens. But Private manages to turn his friends back to his side and they then learn that they can use Private's cuteness as a reverse for the Medusa Serum. Dave and his minions attempt to stop them, but Private punches him with his butt hand (which he developed as a side effect from the serum) and knocks him away. The penguins then use the machine to return all of the penguins back to normal.

Later, Dave is revealed to have also caught in the blast, and as a result, he is shrunk and trapped in a snow globe. He swears revenge against the penguins, but he's interrupted when a little girl picks up his snow globe and proceeds to shake him around. It is unknown what happened to him after this.

Personality
Dave was originally a child friendly zoo animal. He performed silly tricks for children and made them laugh. However, when the penguins stole his glory, he snapped and became an evil and psychotic mastermind. He grew to hate penguins and attempted to take his revenge by turning them all into monsters, hoping it would make the humans dislike them. But shortly following his defeat, he was shown to have a sympathetic feeling toward the little girl that picked him up. However, it's possible he changed his mind when she began to rapidly shake him.

Role in the series
Coming soon... (I may be spoiling part of the movie by publishing this, and I apologize, but what the heck, I'll do it anyway.)