Inspector Gadget, voiced by Don Adams, is a bumbling detective with gadgets built into his body. His fashion sense resembles that of Inspector Clouseau from the Pink Panther movies; his mannerisms also appear to draw on the character of Maxwell Smart, which Adams portrayed in the 1960s.
Often cluelessly stumbling through any case he is given, Gadget frequently ignorantly makes foolish mistakes pertaining to surroundings and current environment, mistaking innocent bystanders (and Brain) for enemies, and believing that the real enemies are friends. His ineptitude always leads him into danger, but he always gets out of trouble through either his trusty gadgets (most notably his springs), Penny's interference, or pure luck.
Penny, voiced by Cree Summer, then by Holly Berger, is Gadget's precocious niece. Inspector Gadget is her guardian and caretaker, though often she seems more suited to be his caretaker due to Gadget's clumsiness. Unknown to any of the recurring characters other than Brain, she is a master of investigation and technology who is the one truly responsible for foiling M.A.D.'s schemes. Penny's principal crime-fighting tool is a high-tech Computer Book capable of breaking codes, surveiling buildings and overriding practically any sort of machine or device. Using the book, Penny is able to monitor Gadget's activities and—with Brain's help—surreptitiously help him avoid numerous potential catastrophes that result from his absent-mindedness while uncovering the true nature of Dr. Claw's plot and foiling it. Penny has blonde hair in pigtails and green eyes, and wears a red and white shirt, green pants and red shoes. She has a number of outfits which are worn for certain assignments or free times rather than her normal clothes. In the second season, Penny mostly wears a jacket. She has a number of the perils and plays the helpless damsel-in-distress role, rescued by Brain usually, and escaping by herself sometimes. In the second season, Penny mostly does not have any perils. Her name is Sophie in the French, Spanish, and German versions and the first airing of the Italian version, Karen in the Israeli version and Lily in a few episodes of the second season of the Polish version.