Dr. Turtlestein is a Alien Turtle scientist appearing in the episode Planet of the Turtles. Donatello and Rupert go to the Planet of the Turtles to look for Dr. Turtlestein, the inventor of the Personal Energy Projector projector, to see if he knows of a way to stop it. Donatello, Dr. Turtlestein, and Rupert come back just in time with a Portable Portal (another one of Turtlestein's inventions) and Donatello reverses the effects of the projector, sending the energy back to Earth. Dr. Turtlestein then uses the transporter to send the Turtles back to Earth.
- His name is a parody of Albert Einstein.