In Hinduism, Atri(Sanskrit: अत्रि) or Attri is a legendary bard and scholar and was one of 9 Prajapatis, a son of Brahma, said to be ancestor of some Brahmin, Prajapatis, Kshatriya and Vaishya communities who adopt Atri as their gotra. Atri is one of the Saptarishi(Seven Great Sages) in the seventh, i.e. the present Manvantara.
Mahanirvana Tantra, translated by Arthur Avalon,(John Woodroffe), 1913, Introduction and Preface shows that The Rishi are seers who know and by their knowledge are the makers of shastra and see all mantras. The word comes from the root rish Rishati-prapnoti sarvvang mantrang jnanena pashyati sangsaraparangva, etc. The seven great Rishi or saptarshi of the first manvantara are Marichi, Atri, Angiras, Pulaha, Kratu, Pulastya and Vashishtha. In other manvantara there are other sapta-rishi. In present manvantara, the seven are Kashyapa, Atri, Vashishtha, Vishvamitra, Gautama, Jamadagni and Bharadwaja. To the Rishi the Vedas were revealed. Vyasa taught the Rigveda so revealed to Paila, the Yajurveda to Vaishampayana, the Samaveda to Jaimini, Atharvaveda to Samantu and Itihasa and Purana to Suta. The three chief classes of Rishi are the Brah-marshi, born of the mind of Brahma, the Devarshi of lower rank,and Rajarshi or Kings who became Rishis through their knowledge and austerities, such as Janaka, Ritaparna, etc. Thc Shrutarshi are makers of Shastras, as Sushruta. The Kandarshi are of the Karmakanda, such as Jaimini.
Atri Gotra originates in the lineage of Brahmarshi Atri and Anasuya Devi(Without-Spite). Anasuya is the daughter of Kardama Prajapati. Brahmarshi Atri is the seer in the fifth Mandala(chapter) of the Rigveda. Atri, also called The Devour-er represents the power of detachment. He is also the Manasa Putra and was born from the mind of Lord Brahma(from his eyes) to assist Lord Brahma in the act of creation. When the sons of Brahma were destroyed by a curse of Shiva, Atri was born again from the flames of a sacrifice performed by Brahma. His wife in both manifestations was Anasuya. She bore him three sons, Dattatreya, Durvasas and Soma, in his first life, and a son Aryaman(Nobility) and a daughter, Amala(Purity), in the second. Soma, Datta and Durvasa are the incarnations of the Divine Trinity Brahma, Vishnu and Shiva respectively. The Trinity channeled their full creative potential through Brahmarshi Atri when they granted boons to his wife Devi Anasuya for helping the Sun to rise in the East every day.(Wikipedia)