Datura is a genus of nine species of highly poisonous, vespertine-flowering plants belonging to the nightshade family (Solanaceae). They are commonly known as thornapples or jimsonweeds, but are also known as devil's trumpets (not to be confused with angel's trumpets, which are placed in the closely related genus Brugmansia). Other English common names include moonflower, devil's weed, and hell's bells. All species of Datura are extremely poisonous and potentially psychoactive, especially their seeds and flowers, which can cause respiratory depression, arrhythmias, fever, delirium, hallucinations, anticholinergic syndrome, psychosis, and even death if taken internally.

Due to their effects and symptoms, Datura species have occasionally been used not only as poisons, but also as hallucinogens by various groups throughout history. Traditionally, their psychoactive administration has often been associated with witchcraft and sorcery or similar practices in many cultures, including the Western world. Certain common Datura species have also been used ritualistically as entheogens by some Native American groups.

Non-psychoactive use of plants in the genus is usually done for medicinal purposes, and the alkaloids present in some species have long been considered traditional medicines in both the New and Old Worlds due to the presence of the alkaloids scopolamine and atropine, which are also produced by Old World plants such as Hyoscyamus niger, Atropa belladonna, and Mandragora officinarum.