1. a character in the British comic The Beano . He is a small boy with untidy hair who is always playing tricks on people and getting into trouble. He has a dog called Gnasher that regularly bites people.
2. a US cartoon character created in the early 1950s. He is a small boy who behaves badly and especially annoys his neighbour, Mr Wilson. Dennis has also appeared in a television series (1959–63) and a film (1993).