Dr. Ivan Krank

Dr. Ivan Krank is the main antagonist in Teacher's Pet: The Movie. He is the uncle of Ian and an evil genius.

Teachers Pet: The Movie
Dr. Krank is first seen on "The Barry Anger Show" where the host interviews him and he says he can turn animals into human beings. Spot finds this as the opportunity to live his dream and goes to see him.

When Spot and Leonard find Krank's lab, he tries to turn a frog into a human but he only makes it 'moo'. Spot arrives and convinces Krank to not destroy the machine and that he needs a mammal to make a man not swamp creatures.

Spot is turned into a human but instead, he's turned into a man not a boy (his age in dog years). Krank then traps Spot and Leonard in a cage to turn them into media freaks.

Then, his nephew, Ian arrives and sets them free in exchange for a chew toy. When Krank finds out, he grounds Ian for the rest of the summer and traps him in a web. He also sends his minons Dennis and Adele to capture Spot.

Later, when Ian calls his parents to take him home, Krank tells him to stay off the phone (he wants to call out for a pizza).

The next night, Leonard arrives at the lab to turn into a dog to be with Spot, but Krank uses him as bait. Suddenly, Spot, Pretty Boy, and Jolly arrive in time to save Leonard. Spot installs the nickel Krank gave him earlier in the machine and it turns him into a mouse and Jolly chases him out of the lab.

When Spot is turned back to a dog, Jolly eats him, therefore killing him and Ian decides to take Dennis and Adele as his cousins. As for Krank, still in mouse form, he is served as a mouse sandwich for Mr. Jolly.

Trivia

 * He's the first Teacher's Pet character to die and get eaten.
 * Kelsey Grammer, who voiced Krank also voices Sideshow Bob in the Simpsons.
 * He was originally going to look like the evil scientist from the Looney Tunes episode, Water Water Every-Hare and the bit more of a character that inspired Danny DeVito.
 * He is the last character to be voiced by Kelsey Grammer, until Henry J. Waternoose, the character that was supposed to be in Disney/Pixar's 2013 animated film, Monsters University.
 * He can take off his head.