The Wizard Police are a band of magical police from Wizard City. They enforce the law and are first seen in "Wizards Only, Fools" where they transform a man pretending to be a wizard into a stick as punishment. They then break into Ron James's shop when he calls them to say that Finn, Jake and Princess Bubblegum are fake wizards. Later, they break into the secret meeting and almost kill Bufo, Laser Wizard, and Forest Wizard before they escape, but succeed in taking Finn and the others to the Grand Master Wizard where he convicts them to be detained to Wizard Prison. They also take Finn, Jake, PB and Abracadaniel there, where there are other the prison guards as well, and try to stop a prison fight between PB and Abracadaniel but end up being frozen by the cold spell.
The Wizard Police are tall wizards with bandanas around their eye, which they can shoot lasers out of. They come in shades of blue, gold, and green.
They apparently can transform any criminals into an object of choice, a stick being the option in "Wizards Only, Fools." They do this by removing their bandanas and emitting a blast of energy out of their one eye. Although non-canon it is shown in "Adventure Time: Finn and Jake investigations" that this transformation is reversible.
They can also fire blasts from their hand, although it's unknown if this blast is lethal like the one from their eyes or if it's merely for making arrests.