Hufflepuff house is haunted by the Fat Friar, who was executed because senior churchmen grew suspicious of his ability to cure the pox merely by poking peasants with a stick, and his ill-advised habit of pulling rabbits out of the communion cup.
Six ghosts are specifically named in the books: the four House ghosts (Nearly Headless Nick of Gryffindor House, the Fat Friar of Hufflepuff House, the Grey Lady of Ravenclaw House, the Bloody Baron of Slytherin House); Professor Binns, the History of Magic teacher; and Moaning Myrtle.
The four ghosts of the Houses are Sir Nicholas (Gryffindor), the Grey Lady (Ravenclaw), the Bloody Baron (Slytherin), and the Fat Friar (Hufflepuff), with one estranged poltergeist annoying them all.
The Gryffindor House ghost was Nearly Headless Nick. He was known as a friendly ghost who was nearly beheaded, but the job was poorly executed, which was how he obtained the nickname of "Nearly Headless Nick". He preferred to be addressed as "Sir Nicholas". His real name was Sir Nicholas De Mimsy-Porpington.
Helena Ravenclaw, the daughter of Hogwarts founder Rowena Ravenclaw. Born in the year 982 she died sometime between the year 996 and 1000. She then became a The Ghost of Ravenclaw known as the Grey Lady. Rowling hid the true identity of the Grey Lady right up until the final instalment of Harry Potter.
The Bloody Baron: Slytherin house ghost
A hot-tempered sort of fellow, who was responsible for the death of the Grey Lady, aka Helena Ravenclaw. In his living days, he was simply known as The Baron. It was only at the point of his death that the 'bloody' part of his name was added in.
In Hogwarts Mystery, Rowan's gender and house always match the player's. As such, Rowan is a Slytherin and female in Star's universe.
In the Chamber itself, we see a large statue of a wizard, which Harry presumes is Salazar Slytherin. We also meet Tom Riddle, who is, as it turns out, the heir of Slytherin. Present only in spirit, he has all the same been controlling Ginny, and having her act as Slytherin's heir.
History of Slytherin
The Head of Slytherin is Horace Slughorn (who left the role to Severus Snape for fifteen years before taking it up again in 1996) and the House's patron ghost is the Bloody Baron.
Moaning Myrtle
Born in the late 1920s to Muggle parents, Myrtle Warren started her Hogwarts life in the early 1940s, where she was sorted into Ravenclaw.
The cup was destroyed by Hermione Granger, using a fang from the Basilisk's corpse.
Hufflepuff refers to one of four Hogwarts houses in the Harry Potter series by J.K. Rowling. Characters are sorted into these houses based on their characteristics, and Hufflepuff is known for having members that are patient, fair, hard-working, and sometimes blandly nice.
Desperate to see her daughter one last time, Rowena sent a man to bring Helena home. Unfortunately, that man was the Bloody Baron, who was head over heels with Helena, and stabbed her in a rage when she refused to come home.
The character (played by Carolyn Pickles) appears briefly in the film Harry Potter and the Deathly Hallows – Part 1. The History of Magic teacher for the entire series, Cuthbert Binns has the distinction of being the only teacher at Hogwarts who is a ghost.
Harry quickly tells Neville that he must destroy Nagini, Voldemort's snake. Nagini is the last Horcrux that Voldemort created and the last one to be destroyed. During the final battle of Hogwarts, Neville pulls the sword of Godric Gryffindor from the Sorting Hat and beheads Nagini, destroying the last Horcrux.
Pansy Parkinson is a member of Slytherin House in Harry's year, with a face like a pug (Harry Potter and the Prisoner of Azkaban). She and Draco Malfoy seem to have a romantic relationship towards the end of the series.
Belonging to the Black family, Phineas is one of Slytherin's loveliest members. Taking a greater moral standpoint than his other family members, who mostly believe in pure-blood supremacy, this good-natured wizard has shown himself to be an especially well-behaved member of the otherwise unruly Hogwarts house.
Myrtle's life was cut shockingly short when she was killed by the Basilisk at Tom Riddle's command.
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.
Harry would have been internally conflicted if he had been Sorted into Slytherin. Although he still would have felt that Hogwarts was the only place he had ever belonged, he might have felt wary forming relationships with the children of Death Eaters.
While the other houses seem cool and invite a certain allure, Hufflepuff is a little different. Often considered the least desirable of all the sorting options, here are some reasons why Hufflepuff house is the worst.
Blood purity
Muggle-born Slytherins existed, but were very rare, as noted insultingly by Scabior the Snatcher. There had also been definite examples of half-bloods sorted into the house, including Tom Riddle, Dolores Umbridge, and Severus Snape.