Drosera subtilis is an annual sundew endemic to northern Australia. The species is named for its slender form.

Drosera subtilis is a small to medium-sized sundew, ranging from 2-18cm in height (most commonly up to 4cm). The plant has leaves with a round lamina and fleshy petioles that extend from an erect stem. Flower stems are produced on the upper parts of the stem, with flowers all facing upwards on one side of the stalk in a helicoid cyme. The flowers are small, white and have four petals. All parts of the plants are glabrous.

The species is endemic to the Northern Territory and Kimberley Region of Western Australia, where it is associated with sandstone habitat. It grows in ephemerally wet skeletal niches such as seepages atop sandstone and sandy washes in moist areas. The plant is a strict wet season species as its habitat relies on almost daily rainfall to stay hydrated, dessicating as soon as regular rain ceases. In the Kakadu National Park, it is very common in the escarpment, but is rarely observed, as most tourism occurs during the dry season. It shares this niche with Utricularia dunlopii.

Genetic studies place Drosera subtilis within the Lasiocephala (petiolaris complex) group of sundews, although it differs from other species (apart from D. banksii) by its strict annual habit. Drosera subtilis is most similar to D. banksii, sharing a similar stature and vegetative morphology. It is readily distinguished by its lack of hairs and stipules, and four-petalled blooms (D. banksii has prominent stipules at the base of the leaves and hairs on the flower stalk and sepals, and is five-petalled).