Vajrasattva (Diamond Being or Adamantine Mind) is a Buddha of Vajrayana Buddhism associated above all with purification. His hundred-syllable mantra and visualization are among the foundational (ngondro) practices of Tibetan Buddhism, undertaken to cleanse negative karma and obscurations before more advanced tantric practice: the practitioner visualizes Vajrasattva above the crown of the head and a stream of purifying nectar washing wrongdoing away. White in colour, he holds the vajra, the diamond-thunderbolt that gives him his name, at his heart and the bell at his hip, the paired emblems of skilful means and wisdom. In some systems he is regarded as a sixth Buddha unifying the five Buddha-families, or as an aspect of Akshobhya, and he stands near the source of many Vajrayana lineages of transmission. Vajrasattva's purification practice traces its scriptural authority to the Guhyasamaja Tantra, among the earliest and most influential of the Anuttarayoga tantras, generally dated by scholars to around the eighth century CE, and the hundred-syllable mantra used in the ngondro preliminaries is drawn directly from that textual tradition.
In the Nyingma school, the oldest of the four main Tibetan Buddhist orders, Vajrasattva is given an even higher status, identified in some presentations with the primordial Buddha Samantabhadra or treated as continuous with him, so the same figure functions, depending on the lineage and level of practice, as either a purifying meditation deity for beginners or an expression of enlightenment's very ground.