Crosby Strickler

Principal Crosby Strickler (voiced by Wallace Shawn) The archetypal mean-spirited and yet incompetent school principal. He despises dogs due to an incident he had with one in fourth grade, and his cat, Tallulah is more than aware that Scott who is a dog by always hissing and scratching whenever he is near. He will not rest untill every child in EastWestland has gone to his school.

Show
When Scott Leadready II arrives, his cat Tallulah knows about Scott being a dog but Strickler can't see the obvious.

In one episode, he reveals he has a sweet tooth.

In another, he leaves Tallulah with Mary to look after her while he's gone. To make matters worse, Tallulah tries to get Spot to reveal himself as Scott. When he gets back, he finds Tallulah a bit messed up and thinks it was Mary and Leonard fault.

In another, when Spot dresses up as his "mom" he starts o flirt with "her". That night, he arrives at Leonard's house to find out the Leadreadys are there. When the Leadreadys "go home", he eats most of Mary's pot roast.

In the final episode, when he and Scott get trapped in a cave, Scott has no choice but to reveal himself as a dog so he can fit through an exit hole. Near the end, he expells Scott because he's a dog.

Movie
In the movie, he lends Mary his RV to travel to a teachers competition but doesn't allow dogs in it.

At the end, he seems to have found out about Scott being a dog.

Future
In the future, he seems to have quit being a principal because of Spot and lives in the old folks home.

Trivia

 * Coincidentally, Principal Mauzar from A Goofy Movie is similar to the guy and is voiced by the same guy.