The Ghosts of Hogwarts: A Quiz

Answer: Nicholas de Mimsy-Porpington

Sir Nicholas de Mimsy-Porpington was the Gryffindor Ghost and was known as 'Nearly-Headless Nick' as he was beheaded, though improperly, leaving his head hanging on to his neck with some skin and sinew. A pretty bad way to be killed, eh?

Answer: 31 October, 1492

He died on 31 October 1492; it is mentioned in his Deathday party in 1992.
He was sentenced to death as he conjured up a tusk on a lady's face betting that he could fix her teeth. He was sentenced to death due to this reason, but the executioner's axe was blunt and could not be sharpened as the grindstone was missing.
Result: A gruesome death with 45 hacks and a cursed not-fully beheaded head.
Consider yourself lucky. :)

Answer: Myrtle Elizabeth Warren

Myrtle Elizabeth Warren was a student in Tom Riddle's schooling days.
In Riddle's sixth year, Myrtle had run into one of the bathroom stalls as a student named Olive Hornby teased her about her glasses. Unfortunately,
Salazar Slytherin, the founder of the Slytherin House's, Basilisk was released by Tom Riddle, the Heir of Slytherin, and made direct eye contact with
Myrtle, resulting in her death. She was not valued a lot by most people, as Myrtle herself says so Harry Potter, who was in his second year:
"Nobody missed me even when I was alive. Took them hours to find my body - I know, I was sitting there waiting for them. Olive Hornby came into the bathroom - 'Are you in here again, sulking Myrtle?', she said, 'because Professor Dippet asked me to look for you -' And then she saw my body... ooooh, she didn't forget that until her dying day, I made sure of that..."
-Myrtle Elizabeth Warren to Harry James Potter, 1992.

Answer: Albania

Helena Ravenclaw, also known as The Grey Lady, was the daughter of
Rowena Ravenclaw, one of the four founders of Hogwarts, and was also the Ravenclaw Ghost at Hogwarts.
Some time after she completed her education at Hogwarts, Helena stole her mother's diadem and escaped to Albania.
Pretty bad relationships... Bet you are feeling blessed for your family. :)

Answer: He died as he was filled with remorse for killing Helena Ravenclaw and stabbed himself with a knife

The Bloody Baron, the Slytherin Ghost, was a man who harbored some unreciprocated love for Helena Ravenclaw, the daughter of Rowena Ravenclaw, one of the four founders of Hogwarts. After Helena stole her mother's diadem and ran away to Albania, Rowena fell fatally ill and sought to meet her estranged daughter and asked the Bloody Baron to bring her daughter in front of her eyes one last time.

The Baron tracked Helena down to a forest and tried forcing her. Despite his efforts, Helena refused to visit her mother, and thus, in a fit of rage, the Baron kills Helena and after realizing what he had done, killed himself. Hot-minded, isn't he?

Answer: Sir Patrick Delaney-Podmore

Sir Patrick-Delaney Podmore is the leader of the Headless Hunt, an army of Headless Ghosts. He makes his first and only appearance in the second book in Nearly-Headless Nick's Deathday party where he steals Nick's moment by starting a game of Head Hockey, thereby spoiling Nick's speech.

He was a very strict leader, considering the fact that he didn't let Nick join the Headless Hunt although Nick was nearly (yet not fully) beheaded.

Answer: The Catholic Church

It is said that the Fat Friar worked for the Catholic Church before he was executed.
The reason for his execution was the fact that the churchmen grew suspicious of his ability to heal a pox of his time by poking peasants on the back with a stick and also his mysterious abilities of producing rabbits from his communion cup. :|

Answer: King Henry VII

Nick worked for King Henry VII prior to his death. He was openly associated with Muggles and King Henry's trust in him made him think that he was a much accomplished wizard than the really was.
I personally wonder how he got into Gryffindor with this mentality... :|

Answer: The Dungeons

The Bloody Baron is the Slytherin Ghost and naturally haunts the dungeons, the place where the Slytherin common room is.
He spent his time there in whole of 1992 school year prowling in the dungeons appearing outside the dungeons only on Nearly-Headless Nick's 500th Deathday Party on 31 October, 1992, not even making an appearance on Christmas Day as he spent day lurking in the dungeons.
Pretty fun-hating man, The Baron, of course, isn't he?

Answer: Scotland

Helena Ravenclaw, the daughter of Rowena Ravenclaw, was jealous of her mother's status and sought to make herself clever and more intelligent than her mother.
Subsequently, she ran away from Scotland, her birthplace, to Albania with her diadem, which later resulted in her death.
This is evident from what she tells Harry in his search for Rowena Ravenclaw's diadem, then a Horcrux of Lord Voldemort:
"I stole the diadem. I sought to make myself cleverer, more important than my mother. I ran away with it. My mother, they say, never admitted that the diadem was gone, but pretended that she had it still. She concealed her loss, my dreadful betrayal, even from the other founders of Hogwarts."
Evidently, she must have had a pretty dumb soul... (hic)...