Lefty is a shady-looking salesman in a trench coat who appears on Sesame Street. He speaks in a whispery voice, and usually tries to sell Ernie such esoteric items as a letter U or O, an invisible ice cream cone, and an empty box. His sales pitches are rarely successful.

In some of his early appeareances, Lefty had slightly hidden angry eyebrows, thus giving him a mean look, but the eyebrows were removed in later sketches.

Although Lefty was primarily performed by Frank Oz, Caroll Spinney played Lefty in at least two segments from Season 1.

Some of Lefty's sketches involved his attempts to carry out assignments from his boss. For these sketches, see Sesame Street Gangsters.

Lefty's boss is the only character who refers to him as "Lefty"; in CTW production materials and Sesame Streetmerchandise, such as storybooks and record albums, he has usually been referred to simply as "The Salesman."

A 2008 book, Storybook ABCs, is the first use of Lefty's name in print. Grover is dressed as Jack (of "Beanstalk" fame), and the Salesman approaches from behind a tree with an offer: "Care for some candy beans for that cow?" Jack replies, "Thanks, Lefty! And do you also have a candlestick?" Lefty apparently has one in stock -- a few pages later, Jack (of "Jack Be Nimble" fame) jumps over the candlestick. At the end of the book, Lefty returns to feed four and twenty blackbirds with birdseed that fills his carry-all bag.