Parselmouths and Parseltongue
Q: Is Parselmouth a real thing or did you make that up?
A: Parselmouth is an old word for someone who has a problem with their mouth like a harelip.
The ability to speak Parseltongue is extremely rare, and is something for which Salazar Slytherin was famous (hence his nickname of "Serpent-tongue", and the choice of a serpent as the symbol of Slytherin House). Tom Riddle inherited this ability from Slytherin, and used it to control the basilisk from the Chamber of Secrets. Harry acquired the ability to speak Parseltongue from Voldemort during Voldemort's attack on the Potters. Harry used the ability unwittingly to speak to a boa constrictor in the zoo (PS2) and to a snake conjured by Draco Malfoy at the Duelling Club (CS11).Known Parselmouths