Mayor Vanderwick

Mr. Vanderwick, or Mayor Vanderwick (formerly), is the sinister mayor of Elmore who was introduced in The End of Elmore fan-fiction saga by wikia contributor WikiStarter. Despite being the mayor only, he controls an army of soldiers who capture Gumball and Tobias. His plans for doing so is unknown, but it may be becuase he wants revenge on Tobias for mishaps caused by him in the past.

Imprisoning Gumball and Tobias
After Gumball, Darwin, Penny and Stacy eavesdropped on Mayor Vanderwick's conversation, they were imprisoned. Gumball and Tobias was not able to get out, and are still imprisoned by Vanderwick.

Relationships
Gumball Watterson

It seems that Mayor Vanderwick, like Principal Brown and Miss Simian, dislikes Gumball, but is not really concerned about him.

Tobias

As shown in The End of Elmore Part 3, it is hinted Mayor Vanderwick and Tobias have confronted each other before - and that Mayor Vanderwick is ready for revenge.

Darwin Watterson

Mayor Vanderwick also has a strong disliking for Darwin and isn't concerned about him.

Emily Cartridge

The two seems to be partners as shown in the last part of The End of Elmore saga. They both work for an unseen "boss".