The MacBoon clan was a wizarding family led by Quintius MacBoon. They lived on the Isle of Drear, and were engaged in a feud with their neighbours, the McClivert clan. They were noted as being particularly inept wizards.
According to legend, after Quintius killed the head of the McClivert clan, Dugald McClivert in a drunken duel, the clan was attacked by the McCliverts and the entire family was Transfigured into Quintapeds. Now more dangerous than ever, the MacBoons proceeded to kill the entire McClivert clan.
Whether or not the legend is true, there are no surviving MacBoons to relay the family story, and the Quintapeds themselves resist all attempts to Untransfigure them. Regardless of the uncertainty, the Quintaped is also known as the "Hairy MacBoon".