Byblis (/ˈbɪblɪs/ BIB-liss) is a genus of carnivorous plants, sometimes termed the rainbow plants for the attractive appearance of their mucilage-covered leaves in bright sunshine. Native to Australia and New Guinea, it is the only genus in the family Byblidaceae. The first species in the genus was described by the English botanist Richard Anthony Salisbury in 1808. Eight species are now recognised.

Byblis species look very similar to Drosera and Drosophyllum, but are distinguished by their zygomorphic flowers, with five curved stamens off to one side of the pistil. These genera are in fact not closely related; modern classifications place Byblis in the Lamiales, while the sundews and Drosophyllum are now placed in the Caryophyllales.

All species of the genus form upright growth supported by a weak, fibrous root system. The genus can be divided into two groups or "complexes": The B. liniflora complex and the B. gigantea complex.

The leaves of all species are round in cross section and highly elongated, tapering at the end. The surface of the leaves is densely studded with glandular hairs which secrete a mucilaginous substance from their tip. These serve to attract small insects, which upon touching the sticky secretions are ensnared. Unless they are strong enough to escape, the insect prey either die of exhaustion or asphyxiate as the mucilage envelops them and clogs their spiracles.

Along with the stalked mucilaginous glands, the leaves are also equipped with sessile glands, which assumedly are responsible for the secretion of the digestive juices. Sessile glands are five to ten times as numerous as the stalked glands.

Byblis were previously grouped among the 'passive flypaper traps' along with Pinguicula, Drosophyllum, Roridula, Stylidium and Triphyophyllum peltatum as the plants were believed to be capable of moving neither their leaves nor tentacles to aid in prey capture or digestion. However, research in 2019 showed that the tentacles of Byblis liniflora collapse following exposure to food, bringing the prey item into contact with the sessile digestive glands. The same behaviour was later observed in B. gigantea.

Flowers in this genus are borne singly at the end of unbranching, leaf-like inflorescences which emerge from the leaf axils. The five-petaled flowers are generally purple to pale violet, though B. gigantea and B. filifolia can sometimes produce white flowers. Except for the self-fertile B. liniflora, all species require pollen from other individuals for fertilization. The pollen release of B. gigantea and B. lamellata is only triggered by the resonance frequency of the wings of a landing pollinator, helping ensure cross-pollination with other individuals. The flowers of Byblis start to bloom in early spring and last until late summer.

Fertilized flowers mature to form an egg-shaped, two-parted seed capsule. As the seed capsule dries out it cracks open (dehisces), dropping the seed on the ground. The black seeds are generally round and often bear webbed surface markings, although those of B. lamellata are strongly ridged. The germination of many species is brought on by bush fires after the dry period; pyrogenic chemicals in the smoke are responsible for triggering germination.