Parseltongue

Parseltongue is the language of serpents (as well as other magical serpent-based creatures, like the Runespoor) and those who can converse with them. An individual who can speak Parseltongue is known as a Parselmouth. It is a very uncommon skill, and is typically hereditary. Nearly all known Parselmouths are descended from Salazar Slytherin.

Page adapted from Parseltongue at the Harry Potter Lexicon.

Characteristics

Parseltongue is, when spoken, a hissing sound, similar to that of a snake; as such, normal people cannot understand it. Apart from merely communicating with serpentine lifeforms, Parselmouths also seem able to influence the will of serpents to a certain extent. Aside from serpent-based creatures, Parselmouths can communicate with each other with the language, the House of Gaunt communicated with each other almost exclusively in Parseltongue.

Reputation

The ability to actually speak Parseltongue is considered an attribute of a Dark Wizard, which is partly due to the fact that both Salazar Slytherin and Lord Voldemort possessed this ability. Another notable Dark Wizard who was also a Parselmouth was Herpo the Foul . However, as Albus Dumbledore pointed out, there are Parselmouths among the good as well, the most well-known of which was Harry Potter.

An unknown member of the Dark Force Defence League once stated when asked regarding the matter by Rita Skeeter - "Personally, I would be highly suspicious of anybody who could converse with snakes, as serpents are often used in the worst kinds of Dark Magic, and are historically associated with evildoers."