Aristides Silk (French: Aristide Filoselle) is a retired civil servant and pickpocket who appears in The Secret of the Unicorn.
He is first shown in the Old Street Market near the start of the story before Tintin purchases The Unicorn model. Silk was moving away from the Thompsons just before their wallets were stolen. When Tintin's wallet was stolen, they found him running away and grabbed his coat, Tintin used the dry cleaners to track where Silk lives and found his house. When the detectives confront Silk, Silk claims to not be a thief, but admits to being a kleptomaniac (someone with an irresistible urge to steal items of a trivial value). He explains to Thompson and Thomson when they come to arrest him that he adores wallets and reveals his large collection, of which none have been emptied of their contents. He is later seen at the end of Red Rackham's Treasure in the Maritime Gallery.