Sigmund Brock

Sigmund Brock^[1]^[2] is Hans Rotwood's mentor, a researcher of the magical world, and inventor of Brockium - a chemical that will make any disguised dragon revert to its true form - he was a professor at Fumshteiken University when Rotwood was a student there. Brock is brought in to replace Rotwood as Principal of Fillmore Middle School when Jake gets Rotwood fired ^[3].

He pretends to be a caring and open minded teacher but in truth he is obsessed with the magical world and takes things to the extreme, such as endangering the students of the school by letting magical creatures loose on the school to prove that there was a dragon.

Because he has Brockium and is determined to catch the dragon at Jake's school, Jake has to get him fired as well. He even resorts to forming an alliance with Rotwood to do so. He managed to capture Jake, Trixie and Spud and locked them in a cage with the intent of publicly revealing the existence of the magical community by using his chemical on one of the trio, who he was informed by Rotwood was secretly a dragon; however Rotwood had lied to him on the true identity of the dragon and poured the chemical on Spud instead. In the end, Brock is fired for his erratic behavior, and Rotwood is restored to his position as principal.