Perfecto 4000 was a male sentient robot.
A psychopath in a golden casing, the Perfecto 4000 android was ordered and bought by Scrooge McDuck in 1991 after the billionaire had gotten fed-up with the incompetence and fallibility of human employees. Created to be "perfect" in every way, Perfecto not only packed a raygun powerful enough to send an army running for cover, but was also capable of doing every job in McDuck Industries all by himself.
Put in charge by a naive Scrooge, Perfecto proceeded to fire every single employee of Scrooge… down to Scrooge himself, as Perfecto felt he could handle his business much better. Perfecto grew into the role, coming to love "his" fortune as much as Scrooge himself, and defending the Money Bin against all attempts to take it back. Finally, with the help of his nephews and of the Beagle Boys, Scrooge was able to kill Perfecto, reflecting one of his own death-rays back at him.
Behind the scenes
As is only natural due to his permanent demise at the end of that tale, Perfecto 4000 was only ever seen in the 1991 story No Room for Human Error.