Although it was briefly speculated in The Chamber of Secrets, Harry is not, in fact, a direct descendant of Salazar Slytherin, though he is still distantly related to him; Voldemort is descended from Slytherin and the second Peverell brother, while Harry is a descendant of the third.
Through his mother's family, he is the last descendant of the wizard Salazar Slytherin, one of the four founders of Hogwarts School of Witchcraft and Wizardry.
Marvolo Gaunt (fl. 1925) was a pure-blood wizard of the House of Gaunt and descendant of Salazar Slytherin. He was the maternal grandfather of Tom Marvolo Riddle (later known as Lord Voldemort) through his daughter Merope, and the great-grandfather of Delphini.
No, he isn't a Dark Wizard. There is no evidence that Salazar Slytherin was a Dark wizard, nor was he interested in the Dark Arts. He built the Chamber of Secrets and hid the Basilisk in there to rid Hogwarts of muggle-borns and half-bloods, because blood-purity was very important to him.
Voldemort was Salazar's heir, and as far as it is explained, he is taking up the mission in the way he believes Salazar had intended, with the Chamber and the Basilisk.
Harry is the magical Heir of Gryffindor (and he's also a descendent of Godric), Neville of Hufflepuff, Hermione of Slytherin and Luna of Ravenclaw. (It was due to Dumbledore's manipulations that Neville and Hermione hadn't been put into the correct House.)
Cast. Maddalena Orcali as Grisha McLaggen, Hogwarts student, and Heir of Godric Gryffindor.
The story of Chamber of Secrets, as you know, is that the Heir of Slytherin has returned and he's out for Mudbloods. The Heir of Slytherin turns out to be Ginny Weasley, who is being controlled via a magical diary that once belonged to Tom Riddle, AKA Voldemort.
In the 1997–1998 school year, Slytherin's heir, Riddle (now known as Lord Voldemort), realised his ancestor's wish of purging the school of Muggle-borns via another method: by taking over the Ministry of Magic and using falsified propaganda.
Her real parents were Daneel and Dean Novak, Pureblooded wizards. Turns out Daneel was Tom Riddles younger sister, Daneel Riddle. Of course, the Riddles were related to Salzar Slytherin himself, and this made Hermione the living heir of Slytherin.
Marvolo was born into the pure-blood House of Gaunt; his son Morfin, and his daughter Merope Gaunt were the last descendants of Salazar Slytherin. Centuries of inbreeding caused poverty and a vein of instability and violence to flourish in the family.
The family was known for producing Dark wizards and witches, including Salazar, Voldemort, and their last descendant, Delphini.
According to Pottermore, you can't learn Parseltongue; a person merely inherits the gene to understand and speak it. Based on all these clues, it looks like Dumbledore is actually related to Slytherin. It would explain why he's never opposed to Slytherin students as some professors are at Hogwarts.
The Heir of Ravenclaw was an individual prophesized by the centaur Harmonthrep (Ajrand) to bring honor and glory to the House of Ravenclaw. The Heir of Ravenclaw was in time revealed to be Brian Dumbledore (Ajrand).
1 Albus Dumbledore
He was revered and respected for his magic and commanding energy, as well as personal strength. It was truly due to Dumbledore's planning that Voldemort died, even if Harry was the one to cast the killing blow because Dumbledore is the most powerful wizard in the entire series.
Harry Potter Would Have Caused Slytherin House To Implode
The influence of Draco Malfoy - who was a prefect for Slytherin - and the perception that Severus Snape was aligned with Lord Voldemort seemingly warped the students into believing they too were part of Voldemort's Death Eaters.
Ginny Weasley was able to speak Parseltongue while she was possessed by Tom Riddle's Diary, which enabled her to open the Chamber of Secrets.
Ginevra Molly Weasley (also known as Ginny) is the youngest child and only daughter of the Weasley family. She is Sorted into Slytherin during Harry and Jim Potter's second year.
It is difficult to say exactly but it does seem like Godric Gryffindor would be more powerful than Voldemort. Voldemort's power was based more on intimidation and fear while Godric Gryffindor did not need that to be considered a great wizard.
Filius Flitwick is one of the many Hogwarts professors that are more powerful than Voldemort. He was a masterful wizard and an experienced professor.
The answer is obviously Merlin, in both universes. In the Harry Potter universe, it would be Merlin because Voldemort wouldn't likely win against Dumbledore and Merlin is alot more powerful than them both.
The Heir of Hufflepuff was none other than Cedric Diggory, who was well on his way to fulfilling the prophecy of the Heir of Hufflepuff when he was tragically murdered by Peter Pettigrew.
Rowena was the wife of Godric Gryffindor and the best friend of Helga Hufflepuff.
"One of the four famous founders of Hogwarts School of Witchcraft and Wizardry, Godric Gryffindor was the most accomplished dueller of his time, an enlightened fighter against Muggle-discrimination and the first owner of the celebrated Sorting Hat."