Duke Senior was a character in William Shakespeare's play As You Like It.
He was usurped by his brother, Frederick, who banished him from the court to the Forest of Arden. In a version of a play staged in the early 17th century which was speculated by The Shakespeare Notebooks to have been unique to a single performance or "perhaps" an extreme example of improvisation by the actors involved, Jaques told Duke Senior about "a fool" he had encountered elsewhere in the forest. When Jacques said he was "ambitious for a motley coat" similar to the fool's, Duke Senior declared "thou shalt have one". (PROSE: As You Like It)