gryffindor
• courageous, brave
founder; godric gryffindor
head of house; professor minerva mcgonagall
house colors; scarlet & gold
house ghost; sir nicholas de mimsy-porpington ("nearly headless nick")
house mascot; lion
location of common room; gryffindor tower, entrance on the seventh floor, located behind a portrait of a fat lady in a pink silk dress. give the fat lady the correct password, and the portrait will swing forward on its hinges, revealing a round opening in the wall leading into the Gryffindor common room, which is the lowest floor of the tower.

hufflepuff
• just, loyal, patient
founder; helga hufflepuff
head of house; professor pomona sprout
house colors; yellow & black
house ghost; the fat friar
house mascot; badger
location of common room; underground in the dungeons, accessed through a still-life painting found near the kitchens. to reach it, you enter a door to the right of the main staircase in the entrance hall and down a staircase there.

ravenclaw
• witty, knowledgable, bright
founder; rowena ravenclaw
head of house; professor filius flitwick
house colors; blue & bronze
house ghost; helena ravenclaw, the grey lady, former fiancιe of the bloody baron (and who was killed at his hand)
house mascot; eagle
location of common room; ravenclaw tower, which is located on the west side of the castle. the entrance is a door at the top of a tightly winding spiral staircase that leads up from the fifth floor. the door has neither handle nor keyhole, but a talking bronze knocker in the shape of an eagle. rather than asking for a conventional password, the knocker will ask a question; if answered correctly, the knocker will compliment the person on the answer and the door will swing open.

slytherin
• cunning, ambitious
founder; salazar slytherin
head of house; professor horace slughorn
house colors; green & silver
house ghost; the bloody baron, killed rowena ravenclaw's daughter helena (the grey lady), the woman he was meant to marry, then committed suicide in remorse
house mascot; serpent
location of common room; under the lake, in the dungeons. the entrance is a hidden door in a blank stone wall, which opens by password. a labyrinth of corridors separates this entrance from the stone staircase leading up to the entrance hall.