The Gray Smurfs were negative duplicates of the original Smurfs that were created by Papa Smurf in order to get his little Smurfs under control and not fighting with themselves all the time. They first appeared in the comic book story "The Smurf Menace". The Gray Smurfs were so named due to the darker tone of the Smurf clothes and skin they wear.
Some of the Gray Smurfs were direct counterparts of the Smurfs, including their leader, the Great Leader (a negative Papa Smurf duplicate who was more authoritarian than paternal), and negative duplicates of Greedy Smurf, Jokey Smurf, a black-haired Smurfette, Handy Smurf, and Brainy Smurf who featured all the negative traits of the originals, yet nothing of the positive ones. They lived in a negative duplicate of the Smurf Village that had a walled fence surrounding its perimeter.
At first, the discovery of these duplicates was purely by accident of some normal Smurfs wandering in the forest. The normal Smurfs tried to be friends with the Gray Smurfs, but the Gray Smurfs were more interested in conquering the normal Smurfs and using them as slaves. As war broke out between the two groups of Smurfs and the normal Smurfs became captives of the Gray Smurfs, Papa Smurf revealed the nature of the Gray Smurfs. However, as the Gray Smurfs now proved to be a threat that must be taken care of, Papa Smurf and his little Smurfs came up with a plan to make the Gray Smurfs disappear for good. With the Gray Smurfs disappearing, the normal Smurfs returned to their village.