Hogwarts is a place of many surprises. Not only are the doors and staircases unusual, but also the paintings on the walls act in ways a visitor might not expect. The paintings are practically full-fledged Beings. They speak and intereact, not just with the humans in the castle but even with each other.
These portraits were not created by the subjects themselves, but by an artist who created the painting during their life. In the case of Hogwarts Headmasters, the portraits were made before their deaths and kept “under lock and key,” occasionally visited by the subject to impart memories and other personality traits to the portrait (Pm). Most of the portraits remain rather dull and two-dimensional, while others have more depth and insight. The artist cannot take credit for a portraits that interact and display complex personality traits — it depends on the magical power of the witch or wizard in the painting (Pm).
Portraits of Previous Headmasters
These portraits apparently spend their days snoozing in the Headmaster’s office (CS12). In fact, often they are faking sleep and listening to everything that goes on; they are duty-bound to help the current Headmaster in any way they can, which usually means traveling to their other portraits on other places and reporting what they see or delivering messages.
- Albus Dumbledore – hangs directly behind the headmaster’s chair, concealing a hiding place (DH33)
- Phineas Nigellus Black – visits his portrait in number twelve Grimmauld Place (OP22, OP23, OP37, HBP23, DH10, DH12, DH33, DH36)
- Armando Dippet (OP22, OP37)
- Dilys Derwent – visits St. Mungo’s, where she had been a Healer (OP22, DH36)
- Everard – visits the Ministry of Magic(OP22, HBP29)
- Dexter Fortescue(DH36)
- Sir Cadogan is a little knight whose picture hangs in a seventh-floor corridor near the South Tower. He is a silly fellow whose bravura outshines his commons sense and who glories in quests and challenges. Sir Cadogan spent some time guarding the Gryffindor Common Room after Sirius Black attacked the Fat Lady (he was the only painting brave enough to take the job). He thought up ridiculous passwords and changed them on a daily basis. He challenged people to duels whenever they would try to enter or leave through the portrait hole. Sir Cadogan has a huge sword and a little fat pony (PA6, PA9) He chased after Harry when Sir Cadogan's picture was hanging on a landing near the North Tower and the Divination classroom, but was stopped in his pursuit when he entered a picture which had a large and angry-looking wolfhound in it (OP12)
- mermaid, painting of
She resembles the mermaids of folklore (that is, like merfolk who live in warm climates such as the Mediterranean Sea) rather than like the merpeople living in Hogwarts' own lake. Her painting hangs in the prefects' bathroom; she apparently flirts with the young gentlemen while they bathe, which doesn't seem to impress Myrtle much (GF25).
- group of women in crinolines, painting of
Hangs on the narrow spiral staircase leading up to Professor Trelawney's classroom in North Tower (PA6)
- Fat Lady, painting of wearing a pink silk dress hangs over the round doorway into the Gryffindor Common Room. To gain admittance to through the portrait hole, a person must give the correct password to the Fat Lady, in which case she swings her frame out from the wall. She has been known to get a bit testy with people who wake her up for no good reason and even to wander off late at night out of her frame to go visiting, making it impossible to get into Gryffindor Tower. She is friends with Violet (GF17). At Christmas, The Fat Lady and Violet tend to consume a good bit of holiday cheer; during Harry's fourth year they got a bit tipsy on chocolate liqueurs (GF23), and over the holidays of Harry's sixth year they drank their way through quite a lot of five-hundred-year-old wine (HBP17).
- monks, painting of a group of
Hangs on the narrow spiral staircase leading up to Professor Trelawney's classroom in North Tower (PA6). At first Harry thought they looked "sinister".
- soppy-looking witch standing in a meadow, painting of
Her painting seems to hang in the Entrance Hall (OP28)
"soppy" in this case means "overly emotional, maudlin, weepy "
- Violet ("Vi")
the Fat Lady's best friend, a wizened, pale old witch whose painting is located in the antechamber off the Great Hall (GF17, 23, HBP17 ).
- walrus mustache, wizard with
His painting hangs next to Violet's in the antechamber off the Great Hall (GF17).
- wizards playing cards
painting located in the Entrance Hall, next to the painting of the soppy-looking witch in the meadow (OP28)
Over the mantlepiece at Aberforth's Hogshead tavern in Hogsmeade hangs the portrait of Ariana Dumbledore, included here because her portrait is connected to the Hogwarts Room of Requirement through a secret passage (DH28). It's not quite clear whether her portrait also hangs at the other end or not - probably not, because the tunnel was created by the Room of Requirement one day when Neville was hungry and thinking about getting food for Dumbledore's Army (DH29). The passageway seems to be included in the painting, as she is able to walk through the tunnel and bring back Neville Longbottom inside the confines of her painting.
"She smiled, turned, and walked away, not as people in portraits usually did, one of the sides of their frames, but along what seemed to be a long tunnel painted behind her. They watched her slight figure retreating until finally she was swallowed by the darkness."
". . . A tiny white dot reappeared at the end of the painted tunnel, and now Ariana was walking back toward them, growing bigger and bigger as she came. But there was somebody else with her now, someone taller than she was, who was limping along, looking excited. His hair was longer than Harry had ever seen. He appeared and torn. Larger and larger the two figures grew, until only their heads and shoulders filled the portrait. Then the whole thing swung forward on the wall like a little door, and the entrance to a real tunnel was revealed. And our of it, his hair overgrown, his face cut, his robes ripped, clambered the real Neville Longbottom..." (DH28).
When Harry killed Voldemort and ended his reign of terror, he went to visit Dumbledore's portrait in the Headmaster's Office and all the other portraits were clapping and cheering him on. But there was a missing portrait - that of Severus Snape, the recently dead Headmaster. If readers were expecting his portrait to magically appear just as Dumbledore's had, they were in for a disappointment because according to the author in her Bloomsbury Live Chat 2007 the other portraits perhaps felt he did not deserve that honor:
Question: Was the absence of Snape's portrait in the headmasters office in the last scene innocent or deliberate?
J.K. Rowling: It was deliberate. Snape had effectively abandoned his post before dying, so he had not merited inclusion in these august circles.
J.K. Rowling: However, I like to think that Harry would be instrumental in ensuring that Snape's portrait would appear there in due course. (BLC)
She was asked about this again during her Carnegie Hall appearance, and reiterated the point that Snape was viewed with distrust, and ironically for the Half-Blood Prince, he wasn't "royal" enough:
Q: Is Severus Snape’s portrait in the headmaster’s office?
JKR: Some have been asking why hasn’t the portrait appeared immediately. It doesn’t. The reason is that the perception in the castle itself and everyone who was in the castle, because Snape kept his secret so well was that he abandoned his post. So all the portraits you see in the headmaster’s study are all headmasters and mistresses who died, it’s like British royals. You only get good press if you die in office. Abdication is not acceptable, particularly if you marry and American. I’m kidding! [laughter] I digress. I know, because I thought this one through, because it was very important to me, I know Harry would have insisted that Snape’s portrait was on that wall, right beside Dumbledore’s. [Applause.]
Inconsistency: JKR's answers still beg the question of why Dumbledore was more worthy than Snape, when Snape was following his orders by "abandoning" his post. Dumbledore let down the school more than once: he left both Harry and the Philosopher's Stone unprotected in Book One, was completely clueless about the Chamber of Secrets even though he understood Parseltongue, hired a dangerous Werewolf in Book Three, completely missed that Moody was Barty Crouch in Goblet of Fire, fled from the Aurors and Umbridge in Book Five, doomed himself to death with the Horcrux ring, and went gadding about searching for Horcruxes without telling anyone his plans in Book Six, before letting Snape kill him. All that happened under Dumbledore's tenure yet his portrait appeared automatically after his death.
Was Snape really worse than Armando Dippet, who gave Tom Riddle a special award for getting Hagrid expelled after Myrtle died, or Phineas Nigellus, the most disliked Headmaster in Hogwarts history? Doubtful.