Each of the four Hogwarts houses has its own ghost. Slytherin boasts the Bloody Baron, who is covered in silver bloodstains. The least talkative of the house ghosts is the Grey Lady, who is long-haired and beautiful. 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. Though a genial character in general, the Fat Friar still resents the fact that he was never made a cardinal. Gryffindor house is home to Nearly Headless Nick, who in life was Sir Nicholas de Mimsy-Porpington. Something of a snob, and a less accomplished wizard than he believed, Sir Nicholas lounged around the court of Henry VII in life, until his foolish attempt to beautify a lady-in-waiting by magic caused the unfortunate woman to sprout tusks. Sir Nicholas was stripped of his wand and inexpertly executed, leaving his head hanging off by a single flap of skin and sinew. He retains a feeling of inadequacy with regard to truly headless ghosts.
(Source: isaidnopeeking, via leylapoth)