Oliver is the pet duckling of Mabel West, the lead character in NHK's Agatha Christie's Great Detectives Poirot and Marple, a television series featuring the works of Agatha Christie adapted into anime format and broadcast in the Japanese language. In the world of this anime series, Mabel West is the sixteen year old daughter of Raymond West who helps both Hercule Poirot and Miss Marple in their cases. Mabel brings Oliver everywhere, usually tucked inside a basket. Oliver usually helps to discover a clue or solve a case.
Oliver is voiced by Japanese voice actress Masako Jo.