Leonard Patrick O'Connor Wibberley, who also published under the name Patrick O'Connor, among others, was an Irish author who spent most of his life in the United States. Wibberley, who published more than 100 books, is perhaps best known for five satirical novels about an imaginary country Grand Fenwick, particularly The Mouse That Roared (1955).

The Mouse That Roared is a 1955 satirical novel by Irish writer Leonard Wibberley, which launched a series of satirical books about an imaginary country in Europe called the Duchy of Grand Fenwick. Wibberley used the premise to make commentaries about modern politics and world situations, including the nuclear arms race, nuclear weapons in general, and the politics of the United States.