For the character appeared in the Smurfs' Village game, go to the page Thief Smurf (real).
Thief Smurf is an identity used in separate occasions by Flying Smurf and Jokey Smurf, yet has only appeared in comics. Whoever is Thief Smurf at the time tends to steal other Smurfs' stuff.
Flying Smurf[]
The first Thief Smurf appears in "The Smurfette" and is, in fact, Flying Smurf ("Schtroumpf volant" in French and not "Schtroumpf voleur"). His name is unchanged in the original language as "voler" in French means either "steal" or "fly". Greedy Smurf makes a cake to give to the Smurfette, but when he goes after a box for the cake, Thief Smurf steals it to be him the one to give it to the Smurfette. However, shortly after Thief Smurf has put the cake in a gift box, Jokey Smurf calls him from the front door, and when Thief Smurf goes to attend, Jokey Smurf enters from the other side, changes the cake for one of his explosive gifts, and leaves. When Thief Smurf unknowingly takes the gift to Smurfette's house, he's intercepted by Greedy Smurf, who opens the gift, believing it's his cake. When it explodes, Greedy says "You were lucky", and leaves.
Much later in the same story, Flying/Thief Smurf is mentioned by Papa Smurf as part of the jury in Smurfette's trial.
Jokey Smurf[]
Technically, Jokey Smurf also becomes a "Thief Smurf" during "The Jewel Smurfer" when he's forced to steal by a human. However, he refuses to steal money since he recalls it just causes trouble, from experience in "The Finance Smurf"