Who Is The Heir Of Slytherin? Harry Potter's Sinister Lineage Explained

Within the "Harry Potter" film franchise, we learn very early on that Hogwarts School of Witchcraft and Wizardry students are separated into four distinct "Houses" that align with their characteristics and desires. The requirements for joining each House correspond to the qualities most valued by the school's four founders; Godric Gryffindor, Rowena Ravenclaw, Helga Hufflepuff, and Salazar Slytherin.

Unfortunately, not all of these founders had their students' best interests at heart. Where founders like Ravenclaw and Gryffindor favored students who showed qualities like "intelligence" and "bravery," the xenophobic Salazar Slytherin prioritized students who were born "pure-blooded" Wizards. This meant that he only accepted students with two Wizard parents, and despised any students who were "Muggle-born." His hatred for Muggle-born wizards was so strong that Slytherin actually hid a Basilisk (a monstrous serpent that can kill with its sight) inside the castle to massacre any Muggle-born students who attended Hogwarts after his death.

Why the other founders would allow a bigoted murderer like Slytherin to even teach at Hogwarts in the first place is beyond reasoning. However, in the end, he succeeded in sealing away the Basilisk in the "Chamber of Secrets," promising that one day his "Heir" would return to the school to exterminate all Muggle-born students. Here's everything you need to know about "Slytherin's Heir," and all the characters in "Harry Potter" who have claim to this title.

The hunt for Slytherin's Heir becomes a major plot point in "Harry Potter and The Chamber of Secrets," when somebody unleashes the Basilisk on the school and leaves a message behind saying, "The Chamber of Secrets has been opened, enemies of the heir ... beware."

Throughout the film, many students suspect Harry Potter (Daniel Radcliffe) of being the Heir of Slytherin due to the fact that he can speak Parseltongue –- the magical language of snakes and serpents. Legend and rumor claim that Parseltongue is an innately dark ability, a well-known trademark of Salazar Slytherin himself.

As such, the Heir of Slytherin can be identified by their ability to converse and control snakes using Parseltongue, and speaking this language is actually directly required to access the Chamber of Secrets. On top of that, Professor McGonagall (Maggie Smith) suggests that the Basilisk itself will only obey the commands of the Heir, saying, "The Chamber is said to be home to something that only the Heir of Slytherin can control." This is important later on since, despite being a Parselmouth, Harry is unable to control the Basilisk when he battles it in the film's climax –- cementing the fact that he is not actually the Heir.

As revealed in the closing moments of "Harry Potter and The Chamber of Secrets," the Heir of Slytherin who returned to Hogwarts and unleashed the Basilisk was none other than Tom Marvolo Riddle (Christian Coulson), known in later life as Lord Voldemort (Ralph Fiennes).

While attending the school in 1942, Riddle released the Basilisk and used it to kill a Muggle-born girl named Myrtle (Shirley Henderson) and later framed Rubeus Hagrid (Robbie Coltrane) for the incident, resulting in Hagrid's expulsion. Like his ancestor Salazar Slytherin, Riddle took measures to ensure that the Chamber of Secrets would be opened again many years after he had left Hogwarts. He did so by sealing a memory of his 16-year-old self in an enchanted diary, which had the ability to possess and manipulate those who used it.

This younger part of Riddle's soul possesses Ginny Weasley (Bonnie Wright) during "Chamber of Secrets," and through her body, he is able to unlock the Chamber and control the Basilisk. Although Ginny technically acted as the "Heir" from the Chamber of Secrets legend (being the one to open the chamber and release the Basilisk) it's important to note that she was not actually the direct descendant of Slytherin. The film and the book both make it very clear that Ginny is merely a vessel for the soul of the true Heir, Tom Riddle, who is actually in control of the Chamber and the Basilisk.

While one could certainly make an argument that Ginny is technically a descendant of Salazar Slytherin (since all Pure-Blood families are technically related, the Weasleys included), the book version of "Harry Potter and The Half-Blood Prince" clarifies that Tom Riddle is the last direct descendant of Slytherin.

We learn this in a memory Harry Potter witnesses in the Pensieve, where Riddle's grandfather Marvolo Gaunt proudly announces that he and his family are the "last living descendants" of the famous Hogwarts founder. This makes Tom Riddle the only true Heir of Slytherin we meet in the "Harry Potter" film franchise, though we do actually meet a second Heir during the events of the canon stage play "Harry Potter and the Cursed Child."

In "Cursed Child," we learn that Lord Voldemort secretly had a child with his loyal follower Bellatrix Lestrange (Helena Bonham Carter), whom they named Delphini. Though the Basilisk perished at the end of "Chamber of Secrets" and Delphini herself never attended Hogwarts, we have to assume that she too would have been able to control the creature just like her father had. Outside of Riddle and Delphini, however, there has yet to be a third confirmed "Heir of Slytherin" within the "Harry Potter" franchise, and it's unlikely we'll see anybody else take up that mantle in future projects.