Bittersweet, Solanum dulcamara, is a species of vine in the potato genus Solanum, family Solanaceae. It is native to Europe and Asia, and widely naturalised elsewhere, including North America, where it is an invasive problem weed. It occurs in a very wide range of habitats, from woodlands to scrubland, hedges and marshes.

It is a semi_woody herbaceous perennial vine, which scrambles over other plants, capable of reaching a height of 4m where suitable support is available, but more often 1-2m high. The leaves are 4-12cm long, roughly arrowhead-shaped, and often lobed at the base. The flowers are in loose clusters of 3-20, about 1-1.5cm across, star-shaped with five purple petals, and yellow stamens and style pointing forward. The fruit is an ovoid red berry about 1cm long, soft and juicy, poisonous to man but edible for birds, which disperse the seeds widely. As with most Solanum species, the foliage is also poisonous for man if eaten.

The name bittersweet is also confusingly used in some areas for some species in the genus Celastrus (the Staff vines, family Celastraceae), e.g. American bittersweet (C. scandens) and Oriental bittersweet (C. orbiculatus).