Mr. Nice Guy
Teenage Mutant Ninja Turtles (1987 TV series) episode
Season Code: 06
Episode: 15
Original airdate December 19, 1992
Written by Steve Granat
Cydne Clark
Episode chronology
← Previous Next →
"Polly Wanna Pizza" "Sleuth on the Loose"
Teenage Mutant Ninja Turtles 1992 Season
List of Teenage Mutant Ninja Turtles episodes


  1. "Rock Around the Block"
  2. "Krangenstein Lives"
  3. "Super Irma"
  4. "Adventures in Turtle-Sitting"
  5. "Sword of Yurikawa"
  6. "Return of the Turtleoid"
  7. "Shreeka's Revenge"
  8. "Too Hot to Handle"
  9. "Nightmare in the Lair"
  10. "Phantom of the Sewers"
  11. "Donatello Trashes Slash"
  12. "Leonardo is Missing"
  13. "Snakes Alive!"
  14. "Polly Wanna Pizza"
  15. "Mr. Nice Guy"
  16. "Sleuth on the Loose"

1987 Season1988 Season1989 Season1990 Season1991 Season1992 Season1992-1993 Vacation in Europe sideseason1993 Season1994 Season1995 Season1996 Season

Mr. Nice Guy is a season 6 episode of the 1987 TV series.


The Turtles are preparing to celebrate Raphael's surprise birthday, and Leonardo is busy icing a cake for him. Michelangelo has purchased him a pair of what he thinks are goldfish, but which are actually Siamese fighting fish. Just then, a cranky Raphael storms in with the laundry, and accidentally crushes the cake with the laundry basket.

Meanwhile, April is ordered to cover increasing crime in New York, and experiences it firsthand when the news van is carjacked. She pursues on a motorcycle.

While Raphael is trying to untangle the iron, he accidentally sets off the Personality Alterator, turning himself sickeningly nice. The other Turtles are surprised and a bit conflicted by the results, since Michelangelo and Donatello find him sickening, but Leonardo enjoys having a more pleasant Raphael around.

The Turtles intervene in a bank robbery taking place with the news van, but Raphael's excessive niceness leads to him helping the criminals in their getaway. After having a pizza, they pursue the bank robbers in a sightseeing bus and have a massive fight at a drive-in theater. The other three Turtles successfully catch the robbers and reclaim the van, but Raphael is busy distributing popcorn to the theater-goers.

On the way home, the Turtles decide to send Raphael to Otto von Shrink, a psychiatrist with state-of-the-art treatments and many robotic attendants. The doctor quickly discovers the source of Raphael's newly nice turn, and orders Raphael to bring the Alterator to him.

Down in the lair, Donatello accidentally sets off the Personality Alterator, which turns the Siamese fighting fish into best friends. Donatello tells the other Turtles what he's figured out, but not before Raphael walks out with the Alterator.

Von Shrink reveals to Raphael that he plans to use the Alterator to steal whatever he desires, because he knows Raphael is too nice to stop him. Police and guards are turned excessively nice and incapable of doing their jobs.

The Turtles soon figure out that Dr. von Shrink is the one stealing things using the Alterator. They infiltrate von Shrink's office and are whisked up to where he is hoarding jewels, furs, paintings and other valuables. He traps them inside a forcefield he calls the Phobia Chamber, which creates holographic representations of their greatest fears.

Donatello manages to throw his bo through the forcefield, triggering the Personality Alterator on the "Normal" setting. Raphael regains his former personality, destroys the Phobia Chamber, and manages to destroy the Enforcer robots sent after the Turtles. He then turns the Alterator on the doctor, making him excessively nice and thus easy to apprehend.

At the lair, they throw a surprise birthday party for Raphael, pleased by his return to his usual rude self.


Major Characters

Minor Characters

  • First Jewel Thief (?)
  • Second Jewel Thief (Townsend Coleman)
  • Museum Security Guard (Greg Berg)
  • Little Boy (Renae Jacobs)
  • First Cop (Pat Fraley)
  • Second Cop (?)

Home media releases


  • Teenage Mutant Ninja Turtles Season 6
  • Teenage Mutant Ninja Turtles: The Complete Classic Series Collection


  • Final appearance of Donatello's Personality Alterator device.


  • Von Shrink's moustache flashes back and fourth from white to flesh-coloured repeatedly when he said he could make/cure millions from the Personality Alterator.
  • Donatello’s Personality Alterator had a plug so Dr. Von Shrink had to weld in a battery pack to make it portable, but in Leonardo Lightens Up the Personality Alterator didn’t have a plug before so it was already portable.


Community content is available under CC-BY-SA unless otherwise noted.