The doppelganger is the main antagonist of the season three of Twin Peaks.
Agent Dale Cooper's doppelganger was created by BOB when he took the soul of serial killer, Window Earle. He then emerged from behind the red curtains, and started laughing maniacally along with BOB. Then the doppelganger runs after Cooper and prevents him from escaping. And then the doppelganger escaped in place of the real Dale Cooper, and left everyone unaware.
Soon after when the doppelganger woke up he asked Cooper's girlfriend, and apologized to her. Just as he was brushing his teeth, he then bangs his head on the mirror on purpose while laughing maniacally. And when Cooper's detectives and colleagues, Sheriff Truman and Dr. Hayward wonder what's going on, while the doppelganger continues to laugh.
After Twin Peaks
Cooper's doppelganger was taken to a hospital because a head injury, there raped Audrey Horne, he then left Twin Peaks and cut off contact with the FBI, who didn't know that was what happened to the real Dale Cooper. Soon after arriving there, he was soon questioned by Cooper's secretary, Diane. He felt her fear and raped her and then created a duplicate of her to assume his identify. Then the doppelganger would return to the lodge after his escape, and along with BOB he created a second duplicate that called him Doggie Jones, hoping that he will be taken back to the inn instead. Soon after 25 years, the doppelganger created its own crime syndicate, and was feared because of its cruelty and cold behevior.
Twin Peaks 2017
Soon after twenty-five years later, the doppelganger contacts former agent Phillips Jeffries saying that the inn will be returned soon, and that Jeffries will be with BOB once again, it bothered the doppelganger who asked if it was really Jeffries on the line. Then the doppelganger became ill and was soon discovered by the police and was taken away. However, the doppelganger manages to escape with the help of one of Ray, who betrays him by shooting him. And soon after the doppelganger is revived, it then soon kills it. After he meets Richard Horne who wants to find another entity called Judy for unknown reasons, however he suspects another trap, Richard is elecrocuted. After the doppelganger returns to Twin Peaks, who gets there, he waits at Sheriff Frank Truman, but Lucy Brennan realizes that the doppelganger is fake Dale Cooper, after Frank calls the real Dale Cooper, she then shoots the doppelganger that he dies. Shortly afterwards BOB exists from him and escapes through a spurt, but prisoner Freddy Dukes destroy the sphere by killing him.
At first the doppelganger had a healthy, and chaotic personality, and technically speaking very similar to BOB, he also does to seem to show any termination of emotion and empathy for the next, making him a psychopath. After season 3 of Twin Peaks, the doppelganger totally changed his personality, but maintaining his cruelty, he was shown to be stoic and calm in risky situations.
- Dale Cooper (doppelganger) is the fourth and last Complete Monster to appear in Twin Peaks, as the others would be Killer BOB, Jean Renault and Window Earle.