The reality police are dark mysterious officers who appeared in the fifty-fourth Goosebumps book, Don't Go to Sleep!.
History
Matt Amsterdam hates his place in life, and the reality police come to him and make him wake up in a different time in the future. High School, Doctor, etc. They try to show him that his reality is not so bad, but Matt is proven guilty by the reality judge.
Other appearances
The reality police do not physically appear in the Goosebumps film, but during the end credits of the film, on A Shocker on Shock Street's animation, there's a street sign that says, "Reality police department". There is also an achievement in Goosebumps: The Game called, "Don't Go to Sleep!".