Her appearance on the Today programme is part of the station's study of fictional characters which includes Springwatch's Chris Packham going to New York on the trail of Avis Giganteus - better known as Big Bird from Sesame Street - and a reunion of the original cast of The Hitchhiker's Guide To The Galaxy for a special performance.
Other shows on Saturday March 29 include best-selling authors Hilary Mantel and Helen Fielding discussing fictional characters and actress Maxine Peake talking to stars including Sally Hawkins and Michael Sheen.
Radio 4 controller Gwyneth Williams said: "What makes some fictional characters stay with us all our lives? Why does it take fictional characters to reveal deeper human truths? And what really brings these characters to life?
"I am delighted to announce anarchy on Radio 4 for a day when some of our favourite characters from drama, literature and comedy will be dropping in and out of the schedule when you least expect it to explore and examine the nature of character."
BBC drama venues around the country will also open their doors, offering fans a behind-the-scenes look at shows including The Archers and Doctor Who.