Rita Skeeter
Age: 44 (According to the dubious Quick Quotes Quill)
House: With her blind ambition and affinity to Slytherins, perhaps she was once in that House, but we don't know.
Distinguishing Characteristics: Blond curled hair, astonishingly large (but manicured) hands and bluntly shaped face, three gold teeth. Carries a crocodile skin handbag and wears faux jewel-studded glasses and lots of make-up, generally set off by brightly-colored robes. (But during her forced sabbatical from journalism, she lets herself go a bit.) Transforms into a fat beetle with designs around her antenna similar to her winged glasses.
First Mention: Goblet of Fire, Chapter 10
General: Rita Skeeter was a prominent journalist in the wizarding world, working mostly as a 'special correspondent' for the Daily Prophet, but sometimes for other publications such as Witch Weekly as well. She wrote to criticize, even to destroy--indiscriminately, it would seem, and subtly, wrapping her wrath in jargon about trying to make the truth known and playing on readers' fears. Her accomplices in this were her photographer Bozo, and her cherished Quick Quotes Quill, a quill as brightly-hued as some of Rita's own garments, that has been bewitched to write its own, highly embellished, versions of "interviews." She's been at it for at least fifteen years, as she was reporting at Ludo Bagman's trial (and seems to think he really did do something wrong).
We heard of Rita's reputation long before Harry actually met her. She wrote the article on the Dark Mark incident after the World Quidditch Cup, criticizing the Ministry of Magic for insufficient security at the event. Apparently she'd previously targeted the MoM for its skewed priorities, legislating over cauldron thickness when there could be vampires at large. The International Confederation of Wizards' Conference also fell victim to Rita's Quill when she wrote an article on it describing Dumbledore as an old dingbat. She had also interviewed Bill Weasley before and insulted his hair style in her article on Gringotts Charm Breakers. She then published a Daily Prophet article questioning Mr. Weasley's assistance to Mad-Eye Moody.
But none of these topics could have been as journalistically promising as The Boy Who Lived. Rita met Harry at the wand weighing ceremony for the Triwizard candidates and proceeded to trap him in a broom closet, perform a rather one-sided interview, and once out of the closet, she had Bozo get as many photos of him as possible. The article (to use the word loosely) she published on Harry's emotional and social sides strove, and succeeded, to touch readers' heartstrings. Harry was unimpresed, as was Dumbledore, as he banned Rita from Hogwarts following the article.
After Harry rebuffed her attempts for another interview after the first task, Rita set her sights on a "bigger" subject: Hagrid. Probably drawn to him by her indefatigable sense for truths being concealed, she reverted to her illegal Animagus disguise and spied at the school as a beetle. She overheard Hagrid revealing his giant heritage at the Yule Ball and this formed the basis for her next big article - and her pivotal row with Hermione. She listened in on enough classes to see who shared her personal vendettas and formed an alliance with Slytherins like Draco Malfoy and Pansy Parkinson. Thus they could give her information in her beetle form.
Rita used her disguise to glean information against Hermione after the second task, and wrote about the supposed love triangle of Harry, Hermione, and Krum for Witch Weekly, strengthening Hermione's determination to find some dirt on Rita herself. Hermione put it all together after Rita's final (for the time being) article for the Daily Prophet, when she described Harry as "disturbed and dangerous." After the third task, Hermione captured Rita as a beetle trying to get the ultimate scoop - the dispute between Dumbledore and Fudge. For the next year, Rita had to refrain from writing altogether, or else Hermione would inform the authorities about her illegal disguise. Rita was able to break her silence only once, to write an accurate article on Harry's Voldemort story for the Quibbler. Over a year passed before Harry saw her, notebook and all, from a safe distance at Dumbledore's funeral, which must mean she is truly reporting again.