An impressionist is a performer whose act consists of giving the "impression" of being someone else by imitating the other person's voice and mannerisms.

The word usually refers to a professional comedian who specializes in such performances, has developed a wide repertoire of impressions, and regularly seeks to add to them, often to keep pace with current events. Someone who imitates one particular person without claiming a wide range, such as a lookalike, is instead called an impersonator. In very broad contexts, "impersonator" may be substituted for "impressionist" where the distinction between the two is less important than avoiding confusion with the use of "impressionist" in painting and music.

Usually, the most "impressive" aspect of the performance is the vocal fidelity to the target — usually a politician or famous entertainer.

Props may also be employed, such as glasses or hats, but these are now considered somewhat old-fashioned and cumbersome: the voice is expected to carry the act.

Because animated cartoons often lampoon famous people (sometimes obliquely), a penchant for impressions has been one of the marks of a successful voice actor. In the U.S., Daws Butler may be the most notable example. Paul Frees made extensive use of an Orson Welles impression.

Impressionists in Britain

During the 1970s British television was awash with impressions of Frank Spencer, a character from a hugely popular British sitcom called Some Mothers Do 'Ave 'Em. This may have been because Frank had such distinctive mannerisms and dress sense which gave performers a number of visual shortcuts to cover for failings in their abilities. At any rate it seemed that, for about a decade, no British impressionist's act was complete without a dose of Frank.

Impressionists were very popular on the televised talent shows of the 1970s; Lenny Henry is a notable example of an act that developed from these roots.

Some notable impressionists

• Carlos Alazraqui
• Ronnie Ancona
• Rory Bremner
• John Byner
• Frank Caliendo
• Jim Carrey
• Phil Cool
• Jon Culshaw
• David Frye
• André-Philippe Gagnon
• Frank Gorshin
• Darrell Hammond
• Will Jordan
• George Kirby
• Rich Little
• Alistair McGowan
• Mike Yarwood