Which of these famous poems is a "Villanelle"?

This is probably the most famous work of the Welsh poet Dylan Thomas (1914-1953) It is a 20th century working of a verse form known as the "Villanelle", a word that comes via Latin from the Italian, meaning "dance" or also "peasant/rustic" although the first Villanelles to still be recorded were written in 17th century France.

The Villanelle form consists of 19 lines divided into five tercets, or three line verses, and one quatrain, or four line verse. The rhyming scheme of the classical Villanelle is also very strict and repetitive, with phrases, too, being repeated.

The very rigidity of the verse form lends itself to poetry dealing with obsession and introspection, although by no means all examples deal with such matters.

Thomas's poem is plainly inspired by the death of his father, but he was to die young himself.

Many other poets have continued to be fascinated by this form, including Sylvia Plath, whose "Mad Girl's Love Song" makes use of it.

The alternative answers are, respectively, examples of Rondo, Ottava Rima, and the Sonnet.