"Do not go gentle into that good night" is a villanelle written by Welsh poet Dylan Thomas (1914–1953), considered to be one of his finest works. Originally published in the journal Botteghe Oscure in 1951, it also appeared as part of his 1952 collection In Country Sleep and other poems.
Written for his dying father, it is one of Thomas's most popular and accessible poems. The poem has no title other than its first line, "Do not go gentle into that good night", a line which appears as a refrain throughout. The poem's other equally famous refrain is "Rage, rage against the dying of the light".