In the fiction of J. R. R. Tolkien, Pipe-weed (also known as Halflings' Leaf) is a tobacco developed by the Shire Hobbit's which became a major industry, especially in the south. Among the Dúnedain it was known as sweet galenas and in Gondor it grew as a wild plant, appreciated primarily for its sweet-scented flowers.

In Gondor it was known popularly as westmansweed, a reference to its origin: it was apparently brought to Middle-earth by Númenoreans during the Second Age. It was first grown among Hobbits by Tobold Hornblower in Longbottom (a region in the Shire) around S.R. 1070 (T.A. 2670). Despite its foreign origins, the Hobbits (possibly those in Bree) were the first to use it for smoking.

Popular varities included Longbottom Leaf, Old Toby, and Southern Star.

The Wizard Gandalf learned to smoke pipe-weed from the Hobbits and was often seen blowing smoke-rings. Saruman initially derided him for this, but at some point he took up smoking himself. After the destruction of Isengard, pipe-weed was found among its stores, but the Hobbits Merry and Pippin missed the sinister implications of the discovery that Saruman had had commerce with the Shire.