The Lone Smurf was a character that appeared in the episode "The Smurfette", who, in reality, was Smurfette masquerading herself as a male Smurf. As the Lone Smurf, she wore a mask and a white long-sleeved shirt with Smurf pants cinched with a black belt and gloves.
She appeared to Gargamel and Azrael as the Lone Smurf to rescue her fellow Smurfs from him, taunting him by saying that he hasn't captured all the Smurfs. Azrael chased after the Lone Smurf, who proved too quick and agile for him to catch, and ended up being led straight back to Gargamel, keeping them too busy with each other while the Lone Smurf freed every Smurf from the box that they were trapped in. After that, the Lone Smurf taunted Gargamel and Azrael to follow her up a tree, which they did until she tricked them into pouncing unto her at the top of the tree and causing them to fall down until they hit the ground, unconscious.
After the Smurfs had made their escape from Gargamel and Azrael, the Lone Smurf appeared unto them and removed the costume to reveal that their rescuer was Smurfette in disguise.