Under Milk Wood was originally a radio play and later a stage play by Dylan Thomas.

The storyteller invites the audience to listen in on the dreams of the fictional small Welsh village of Llareggub (the name is "bugger all" spelt backwards, but appeared in print as Llaregyb so as not to offend), and their innermost thoughts and dreams are laid bare to us. There is Mrs. Ogmore-Pritchard, relentlessly bossing her two dead husbands; Captain Cat reliving his seafaring times; the two Mrs. Dai Breads; Organ Morgan, obsessed with his music; Polly Garter pining for her dead lover. Later, the town wakes and we see them go about their daily business, aware of how their feelings affect whatever they do.

When Dylan Thomas was staying in New Quay one winter, he went out early one morning into the still sleeping town and verses came to his mind about the inhabitants. He wrote up the account of this as Quite Early One Morning in 1944, and recorded the story for radio in 1945. He continued to work on the idea for eight years, and on 9 September, 1953, he delivered a full draft of Under Milk Wood to the BBC as he left for a tour of America, intending to revise the manuscript on his return. He read a part of the script in public for the first time in Cambridge, Massachusetts. Two months later he was dead. The play was recorded by the BBC in 1954. The recording featured Richard Burton as 'First Voice'.

Thomas' poetic writing and an unforgettable cast of characters makes this a landmark play in the history of both radio and theatre. It was later made into a film (1972), with Richard Burton reprising his role, and other parts played by Elizabeth Taylor, Peter O'Toole, Glynis Johns, Vivien Merchant, and other well-known actors, and Ryan Davies as the 'Second Voice'.

In November 2003, as part of the their celebration of the fiftieth anniversary of Thomas's death, the BBC broadcast a new production of the play, imaginatively combining new actors with the original 1954 recording of Richard Burton playing 'First Voice'. (Broadcast November 15 2003, BBC Radio 4; repeated December 24 2004.) Digital noise reduction technology allowed Burton's part to be seamlessly incorporated into the new recording, which was intended to represent Welsh voices more realistically than the original.