It would be easy to think that if you were an actor in a movie or on a long-running beloved TV show that you would have fond memories of your time filming the movie or show. It would be easy to think that you might remember your most famous lines and the plot of the movie or TV series. It would be easy to think that if you received an award for your role on the show that you would remember attending the awards show. Unfortunately, this is not the case for all actors.

Some actors have absolutely no memory of filming their most famous roles. They don’t remember the plot. They don’t remember being on set. They don’t remember the script. They may have vague memories of the friends they made on set, but that’s about it.

There are different reasons for this memory loss. In some cases it’s due to a health issue. In some cases it’s due to drug abuse. In other cases, the actors simply say they have a bad memory.

Scroll down to see examples of 13 actors who don’t remember their most famous roles.

1. Matthew Perry

   Matthew Perry doesn’t remember 3 years of the show “Friends.” He doesn’t remember most of seasons 3 through 6. He says this memory loss was due to addiction problems.

2. Courtney Cox

   The actress who played Monica has no memory of playing Monica. She actually rewatched “Friends” to try to jog her memory. She simply blames having a bad memory.

3. Raven-Symoné

   As a child, Raven-Symoné played Olivia on “The Cosby Show.” She has no memory of this role which she played between the ages of 4-6. In therapy, she’s trying to figure out why she doesn’t remember filming this show. She told “Uncensored,” “I don’t remember a scene. I don’t remember anything while it’s a rehearsal or a camera… I do not remember as soon as the cameras start. Something clicks off, and I do what I’m trained to do.”

4. Frankie Muniz

   From the age of 15-20, Frankie Muniz played Malcom on the show “Malcom in the Middle.” He has no memory of this role, and he doesn’t remember going to the Emmy Awards when he was nominated for his performance on the show. He blames the fact that he has had 9 concussions in his life, the first at age 7 when playing soccer. He has also had 15 transient ischemic attacks (or TIAs). These are also known as mini strokes.

5. Avan Jogia

   Avan Jogia has no memory of filming the show “Victorious.” He does; however, remember going out and getting drunk after filming the show. He blames his memory loss on being hungover.

6. Ethan Embry

   Ethan Embry was stoned the entire time he was filming “Can’t Hardly Wait.” He has no memory of anything about this movie. He says he never even read the script.

7. Colin Farrell

   Colin Farrell doesn’t remember anything about filming “Miami Vice.” He blames drug and alcohol addiction. He went to rehab right after the movie was finished filming.

8. Brie Larson

   Brie Larson has no memory of one of the most famous scenes in the movie “Room,” which earned her an Academy Award. She told The Denver Post, while she was filming the scene where she reunites with her son, “I slipped and fell on the ice, and then, when I went to dive into the police car, I guess I hit my head.”

9. Malcolm McDowell

   Malcolm McDowell is a British actor who acted in movies including “A Clockwork Orange” and “Easy A.” He has no memory of most of his roles. This could be partly due to the fact that he has acted in upwards of 300 movies.

10. John Boyega

    John Boyega won a Golden Globe for his role in “Small Axe.” He has no memory of filming the scene where his character discovers racist graffiti on his police locker. He only remembers being angry.

11. Michael J. Fox

    Michael J. Fox has hardly any memory of filming “Back to the Future.” He thinks this is due to the fact that he was filming this famous movie at night while also filming the TV series “Family Ties” during the day. He must have been incredibly sleep deprived.

12. David Bowie

    Okay, so David Bowie isn’t an actor, but we think this still counts. He has no memory of recording the 1976 hit “Station to Station.” He was using a lot of cocaine at the time.

13. Stephen King

    Okay, again, not an actor, but a lot of his books have become movies, so again, we think it counts. Stephen King has no memory of writing “Cujo.” He thinks this is due to cocaine use.