Dr. Mario

Dr. Mario is the persona Mario takes in the Dr. Mario series of games. Under this character, Mario dons a lab coat, a head mirror and a stethoscope around the neck. He first appeared in Dr. Mario, and the Dr. Mario series has expanded to new consoles and handhelds by Nintendo. Dr. Mario has additionally appeared as an unlockable fighter in Super Smash Bros. Melee.

Princess Peach functions as Dr. Mario's assistant nurse, also known as Nurse Toadstool in localizations of the original game manual. She also appears (or is at least mentioned) in versions of the game. As mentioned in the original game manual, Dr. Mario and Nurse Toadstool work at the Mushroom Kingdom Hospital. Dr. Luigi also appears in his own game, as a spin-off to Dr. Mario.