A damaru (Sanskrit: डमरु, IAST: ḍamaru; Tibetan ཌ་མ་རུ་ or རྔ་ཆུང) is a small two-headed drum used in Hinduism and Tibetan Buddhism. In Hinduism, the damaru is known as the instrument of the Hindu deity Shiva, associated with Tantric traditions. It is said to be created by Shiva to produce spiritual sounds by which the whole universe has been created and regulated. In Tibetan Buddhism, the damaru is used as an instrument in meditation practices.

The damaru is typically made of wood, metal with leather damaru heads at both ends. The resonator is made of brass. Its height ranges from a few inches to a little over one foot. It is played single-handedly. The strikers are typically beads fastened to the ends of leather cords around the waist of the damaru. Knots in the leather can also be used as strikers; crocheted material is also common. As the player waves the drum using a twisting wrist motion, the strikers beat on the drumhead.

The damaru is very common throughout the Indian subcontinent. It is associated with the Hindu deity Shiva. It is believed that Sanskrit language was recognized by the drumbeats of the damaru (see Shiva Sutra for the sounds), and his performance of the cosmic dance of tandava. The damaru is used by itinerant musicians of all stripes, due to its small portable size.

In the post-Mauryan period a tribal society at Kosambi (modern Prayagraj district) made cast copper coinage with and without punchmarks. Their coinage resemble the damaru-drum. All such coinage has been attributed to the Kosambi. Many Indian museums, such as the National Museum, have these coins in their collections.

In the Tibetan Buddhist tradition, the damaru is part of a collection of sacred implements and musical instrument was adopted from the tantric practices of ancient India. These reached the Himalayas from the 8th to 12th century, persisting in Tibet as the practice of Vajrayana flourished there, even as it vanished in the subcontinent of India.

The skull (thöpa) damaru is made from a male and female skull bone or calvarium, cut well above the area of the ear, and joined at their apex. Inside, male and female mantras are appropriately inscribed in gold. The skins are traditionally cured by burying them with copper and other mineral salts, and special herbal formulas for about two weeks. These are then stretched and applied to the two sides, giving the skins their familiar blue or green mottled appearance. A collar of simple brocade, or copper or silver, has a hand-hold, and is the site of attachment of the beaters, whose knit cover represents two eyeballs. The skulls are also carefully chosen for their attributes and source. After the Tibetan diaspora in 1960, they began to be manufactured in India and Nepal, with a continued degradation of quality. Today, India is no longer a source, and their creation and export from Nepal are banned, because of the acquiring of human bone through illegal practices. One still does find occasionally those with painted skins and without the proper mantras or other characteristics.

The symbolism and energetic properties of the drums is extensive. These human skull damaru or chang te'u are used in a wide range of Vajrayana ritual, as a standard right hand accompaniment to the bell, held in the left hand. Usually used together as an accent or punctuation during various tantric practices, the drum can also keep time during entire passages. For the solo practitioner, it is an essential tool, while in larger assemblies, only the presiding Rinpoches and chant masters use them, in concert with the long horns (radung), short horns (gyaling), large cymbals (silnyen and rolmo) and large temple drums (lag-na).

The Chöd drum (or chöda) is a specialized form of damaru. It is generally larger in circumference and has a more round shape than its smaller counterpart. The Chöd drum is used in the tantric practice of Chöd.