By the time Goblet of Fire came out, J.K. Rowling had gotten a huge dose of fame. She had been a bestselling writer for three years, and her books were already known as a publishing phenomenon. Thus, it makes sense that a lot of journalists saw pointed criticism of the press in the depiction of Rita Skeeter, evil journalist extraordinaire. Maybe J.K. Rowling included Rita Skeeter in Book 4 because she knew people like Rita by then? But no! J.K. Rowling insists that she had always planned to have a character of this kind in her fourth Harry Potter book:
[W]hen I got the point in the writing where I had to introduce Rita, I did hesitate, because I thought, People will think this is my response to what's happened to me. But I had a lot more fun writing Rita than I think I would have done if it hadn't happened to me. (source)
So even though Rita Skeeter had been planned from the beginning, J.K. Rowling might have written her with a bit more zest once she knew so many more journalists like Rita in real life. There's something a bit ironic about J.K. Rowling writing about the burden of Harry's fame just as she herself is beginning to feel her own fame. Even if the resemblance is unintentional, we think it's worth pointing out.
Rita Skeeter has always been an essential part of the Harry Potter series. In a BBC special, J.K. Rowling also revealed,
Originally, Rita Skeeter turned up in Book One. Harry enters the Leaky Cauldron, which is the place where he gets his very first taste of how famous he is. For the first time it hits him. And there's a very early draft of that chapter, in which Rita made a beeline for him. But this gutter journalist fits better in Book Four, which when the pain of fame starts to drag at Harry. (source)
Rita Skeeter is the worst kind of journalist because she's more interested in generating an exciting story than in telling the truth. She also has absolutely no qualms about exploiting someone to sell papers. When she "interviews" Harry about being the second Hogwarts Triwizard champion, she presents him as a weepy, tragic orphan – absolutely the last public image Harry wants. Later, when Hermione shouts at Rita Skeeter for outing Hagrid as a half-giant (and making it sound like he's dangerous), Rita Skeeter abuses her position as a reporter to get back at Hermione. She publishes an article saying that Hermione is stringing along two famous young men, Harry and Viktor Krum. Even though Hermione laughs off the article, she starts getting hate mail from people who really do think she's a bad person.
Worst of all, when Harry firmly turns his back on Rita Skeeter, she prints a piece claiming that Harry is dangerously unbalanced. She implies that he's lying about his curse scar pain in order to get attention, and she includes a quote from Draco Malfoy: "[H]e's made friends with werewolves and giants too. We think he'd do anything for a bit of power" (31.48). Harry tries to laugh off this article the way Hermione shrugs off Rita's earlier love triangle piece, but it still proves to have serious effects. Cornelius Fudge uses Rita Skeeter's article as a way to cast doubt on Harry's account of what happened to him in the Little Hangleton graveyard. He strongly implies that Harry is subject to hallucinations, and that he's just imagining the return of Voldemort.
Hermione comes up with a way to control Rita Skeeter by the end of Goblet of Fire. She realizes that Rita is an Animagus, a wizard that can change into an animal. All wizards capable of this transformation are supposed to register their Animagus form with the Ministry of Magic. But Rita Skeeter has never done so. Her secret form is a beetle, and she uses this small, easily ignored body to spy on private conversations and publish them openly. That's how Rita Skeeter found out about Hermione's relationship with Viktor Krum and Harry's fit of scar pain during Divination class.
In exchange for keeping quiet about her unregistered Animagus form, Rita Skeeter has to promise not to publish any lies about anyone for a whole year. Hermione wants her to "see if she can't break the habit of writing horrible lies about people" (37.107). But we have the strong suspicion that it will take more than a spot of well-intentioned blackmail to keep Rita Skeeter from writing "horrible lies." It's her thing, after all, it's what she does.