The Comprachicos (meaning "child-buyers") were a literary invention of Victor Hugo used in his famous tragedy "The Man Who Laughs" - they were based on folklore concerning travelling bands of people who were believed to kidnap and mutilate children.
In "The Man Who Laughs" a gang of these criminals kindapped the main protagonist as a child and horrifically scarred him, making him appear as if he had a permanent smile (via removing large portions of his lips).
Victor Hugo gave the following as a description of these gruesome individuals:
"The Comprachicos worked on man as the Chinese work on trees. A sort of fantastic stunted thing left their hands; it was ridiculous and wonderful. They could touch up a little being with such skill that its father could not have recognized it. Sometimes they left the spine straight and remade the face. Children destined for tumblers had their joints dislocated in a masterly manner; thus gymnasts were made. Not only did the Comprachicos take away his face from the child; they also took away his memory. At least, they took away all they could of it; the child had no consciousness of the mutilation to which he had been subjected. Of burnings by sulphur and incisions by the iron he remembered nothing. The Comprachicos deadened the little patient by means of a stupefying powder which was thought to be magical and which suppressed all pain."
After mutilating their victims the Comprachicos often sold the children to freak-shows or forced them to beg for money.