Federal Bureau of Investigation Special Agent Dale Bartholomew Cooper, portrayed by Kyle MacLachlan, is a fictional character who is the protagonist of the ABC television series Twin Peaks and its 2017 revival series by Showtime. He also plays a supporting role in the prequel film Twin Peaks: Fire Walk with Me.
An eccentric FBI agent, Cooper arrives in Twin Peaks in 1989 to investigate the brutal murder of popular high school student Laura Palmer.
Cooper displays an array of quirky mannerisms such as giving a "thumbs up" when satisfied, sage-like sayings, and distinctive sense of humor along with his love for a good cherry pie and a "damn fine cup of coffee" which he takes black. One of his most popular habits is recording spoken-word tapes to a mysterious woman called "Diane" into his microcassette recorder that he always carries with him, that often contain everyday observations and thoughts on his current case.
All information taken from Wikipedia