JK Rowling, Cheltenham Literature Festival, 1998.
I was ten, and she was my hero. Potter was popular, but hadn't yet taken off in the way it would soon after; at that point, she had only released the first two books. There were about 150 seats in the room, I believe, and not all of them were full. Quite ridiculous now, when you think about what was to come!
I think more than a few people here will be pleased (but not surprised) to hear that she was wonderful. She read us the passage from Chamber of Secrets where Harry meets Dobby, complete with voices. Then she answered questions. I asked what the next book would be called and she said it was Harry Potter and the Prisoner of Azkaban.
Finally, she spent ages signing books with lovely personalised messages while everyone queued up for their turn. When my very confident friend piped up that I had handed my battered copy of Philosopher's Stone round the school so extensively that it had fallen apart, she signed my books as you will see in the pictures.
That meant the world to me at 10 and still does.