Dual role (also known as Double role) refers to one actor playing two or more roles, which may be deliberately scripted in a play or film, or merely be a by-product of a low budget in one particular production. In a theatrical production where more than one actor plays multiple characters, it is sometimes referred to as an "Ironman" cast.

In theater, such as in the works of absurdists such as Tom Stoppard, characters played by the same actor may be of thematic significance. A good example of this is Tony Kushner's Angels in America, which has a cast of eight despite having many roles. Debate exists over William Shakespeare's use of such, with a famous example being whether the characters of Cordelia and the Fool in King Lear are one and the same. In stage productions of Peter Pan, it is a tradition for Mr. Darling and Captain Hook to be played by the same actor, a tradition often continued in film adaptations.

In film, this technique has often been used for comic effect (though not always, as were Nicolas Cage's Academy Award-nominated roles in the film Adaptation.), examples being Peter Sellers in movies such as Dr. Strangelove and Mike Myers in the Austin Powers films. Tamil actor M.N.Nambiar has donned 11 roles in the film Digambara Samiyar. Indian actor Kamal Hassan played 10 roles for the movie Dasavathaaram. Sivaji Ganesan, has acted 9 roles in the tamil film Navarathiri.Buster Keaton infamously played nearly every part in his 1921 film The Playhouse. Alec Guinness played all eight members of one family in Kind Hearts and Coronets. In The Nutty Professor and its sequel, Eddie Murphy played the title character and almost every member of his family.