"I have never been tempted to kill him off before the final because I've always planned seven books, and I want to finish on seven books," Rowling said on Monday's "Richard and Judy" television show.
"I can completely understand, however, the mentality of an author who thinks, `Well, I'm gonna kill them off because that means there can be no non-author written sequels. So it will end with me, and after I'm dead and gone they won't be able to bring back the character'."
Rowling declined to commit herself about Harry, saying she doesn't want to receive hate mail.
"The last book is not finished. But I'm well into it now. I wrote the final chapter in something like 1990, so I've known exactly how the series is going to end," she said.
Rowling said people are sometimes shocked to hear that she wrote the end of book seven before she had a publisher for the first book in the series.
"The final chapter is hidden away, although it's now changed very slightly. One character got a reprieve. But I have to say two die that I didn't intend to die," she said. "A price has to be paid. We are dealing with pure evil here. They don't target extras do they? They go for the main characters. Well, I do."
Rowling is the richest woman in Britain — wealthier than even the queen — with a fortune estimated by Forbes magazine last year at more than $1 billion.
Whatever she writes next, Rowling is sure of one thing: It won't be as successful as Harry Potter.
"I don't think I'm ever going to have anything like Harry again. You just get one like Harry."