Dementor Attack
Order of the Phoenix begins with a Dementor attacking Harry and Dudley in Little Whinging (a Muggle community). Dementors are accompanied by a loss of happiness, coldness, and darkness. This image at the beginning sets the tone for a darker novel than the four before it. At the end of Harry's fourth year, Voldemort was reborn, signifying dark times ahead. The Dementors personify the degradation that is beginning in the Wizarding World.
The Fountain of Magical Brethren
The Fountain of Magical Brethren is a sculpture depicting the magical community and how they are viewed by witches and wizards. The pool has a group of golden statues in the middle. The tallest statue is a wizard, placed in the middle with the others, a witch, centaur, goblin, and house-elf, surrounding him. The centaur, goblin, and house-elf are looking up at the wizard and witch in adoration. The image conveyed here is superiority through a ranking system. The wizard is bigger (ergo better) than the witch, but the wizard and witch are superior to the others, which is why the non-humans are looking up to them in adoration. In reality, the centaur is larger than the witch and wizard, goblins hold disdain for wizards and witches in general, and house-elves posses more powerful magic than humans.
The Fountain of Magical Brethren is described in Chapter 7 and Chapter 36.
Mrs. Weasley's Boggart
The Boggart that Mrs. Weasley faces takes on the image of her family members and Harry (who she considers a son) dead. This imagery personifies Mrs. Weasley's true fears, the return of the dark times and facing untold losses again. Lupin attempts to ease her fears by reminding her that they are much better prepared than they were the previous time. She is embarrassed by the encounter and doesn't want Arthur to know. She knows that they must all resist Voldemort and his Death Eaters. Telling Arthur her fears would lead to him consider leaving the Order. She writes the encounter off as worrying too much and being silly. This paints an image of a loving mother and wife wanting to protect her family but restraining that desire for the greater good.
The Boggart encounter occurs in Chapter 9.
Mrs. Black's Portrait
Sirius' mother has a portrait permanently stuck to the wall at Number 12, Grimmauld Place. The painting is behind "a pair of long, moth-eaten curtains" (29). The painting is described as one of the most life-like that Harry has ever seen. In the portrait, Mrs. Black is an old woman. When Tonks knocks over the umbrella stand, the curtains fly back and the woman was "drooling, her eyes were rolling, the yellowing skin of her face stretched taut as she screamed" (37). Aside from screaming and shrieking, Mrs. Black also screams racial slurs such as "Mudblood," which is directed at Muggle-borns and blood-traitors, referring to the Weasleys because they are pure-bloods associating with Muggle-borns.