Mr. Ree (also known as Toilette Ree) is the school janitor and a former member of T.E.R.D.S. introduced in The Epic Tales of Captain Underpants.
Mr. Ree originally was hired by the government to make T.E.R.D.S (Toilet Eliminator of Really Dangerous Stuff) in the late 1990s. However, during the first official test flush, the handle got stuck, resulting in a massive flood that injured and possibly killed many. They were shut down, and Mr. Ree abandoned T.E.R.D.S in his past.
In "The Terrifying Perilous Misfortune of the T.P. Mummy, he becomes a janitor at Jerome Horwitz Elementary School. With George and Harold's help, he gets the courage to use T.E.R.D.S. to defeat the T.P. Mummy. He later appears to be crushing on Ms. Yewh at the end, much to Mr. Krupp's dismay.
In "The Shadowy Syndrome of the Sinister Splotch", the titular villain takes control of his mind and body and uses his skills of invention to create bed of roses and a dryer sheet that allows him to control all robes, along with the wearer's said robes. He then begins committing crimes while posing as Captain Underpants in order to frame and get rid of him. Luckily, George, Harold, and Captain Underpants manage to defeat the villain near the end, saving him.