Not I is a short dramatic monologue written in 1972 (20 March to 1 April) by Samuel Beckett which was premiered at the "Samuel Beckett Festival" by the Repertory Theater of Lincoln Center, New York (22 November 1972).

Not I takes place in a pitch-black space illuminated only by a single beam of light. This spotlight fixes on an actress's mouth about eight feet above the stage, everything else being blacked out and, in early performances, illuminates the shadowy figure of the Auditor who makes four increasingly ineffectual movements "of helpless compassion" during brief breaks in the monologue where Mouth appears to be listening to some inner voice unheard by the audience.

The mouth utters jumbled sentences at a ferocious pace, which obliquely tell the story of a woman of about seventy who was abandoned by her parents after a premature birth and has lived a loveless, mechanical existence, and who appears to have suffered an unspecified traumatic experience. The woman has been virtually mute since childhood apart from occasional outbursts, one of which comprises the text we hear. From the text it could be inferred that the woman had been raped but this is something Beckett was very clear about when asked. "How could you think of such a thing! No, no, not at all—it wasn’t that at all." It seems more likely that she has suffered some kind of collapse, possibly even her death, while "wandering in a field … looking aimlessly for cowslips."

The woman relates four incidents from her life: lying face down in the grass, standing in a supermarket, sitting on a "mound in Croker's Acre" (a real place in Ireland near Leopardstown racecourse) and "that time at court", each being preceded by a repeat on the repressed first ‘scene’ which has been likened to an epiphany; whatever happened to her in that field in April was the trigger for her to start talking.

Her initial reaction to the paralyzing event is to assume she is being punished by God but finds she is not suffering; she feels no pain, as in life she felt no pleasure. She cannot think why she might be being punished but accepts that God does not need a "particular reason" for what he does. She thinks she has something to confess and believes that if she goes over the events of her life for long enough it will be revealed to her. In addition to the continued buzzing in her skull there is now a light of varying intensity tormenting her; the two seem related.

The title comes from the character's repeated denial that the events she describes or alludes to happened to her.

Beckett had always intended that Billie Whitelaw, whom he had worked with on Play, give the definitive premiere performance of Not I. "But in the end, more out of friendship than because of any delays in London, he allowed Alan Schneider the opportunity to present it first" in America featuring Jessica Tandy. Tandy did fly to France to discuss the text with Beckett. However, Whitelaw’s subsequent performances benefited from extensive coaching from Beckett.

"I knew that woman in Ireland," Beckett said, "I knew who she was — not 'she' specifically, one single woman, but there were so many of those old crones, stumbling down the lanes, in the ditches, besides the hedgerows." That said, Beckett did not demand that the part be spoken with an accent, his one concession to Whitelaw when tutoring her. Schneider put ten questions to Beckett, indicative of his bafflement. Beckett responded: "I no more know where she is or why thus than she does. All I know is in the text. 'She' is purely a stage entity, part of a stage image and purveyor of a stage text. The rest is Ibsen."