Gowthama : Gowthama was one of the Maharishis of Vedic times, known to have been the discoverer of Mantras -- 'Mantra-drashtaa', in Sanskrit.He was the son of Rahugana, belonging to the line of Angiras. The Devi Bhagavatam says that the river Godavari is so named because of its association with Gautama. He had two sons by name Vamadeva and Nodhas, both themselves discoverers of Mantras.
Kasyapa : Kasyapa was the father of the Devas, Asuras, Nagas and all of humanity. He married Aditi, with whom he fathered Agni, the Adityas, and most importantly Lord Vishnu took his fifth avtar as Vamana, the son of Aditi, in the seventh Manvantara. With his second wife, Diti, he begot the Daityas. Diti and Aditi were daughters of King Daksha Prajapati and sisters to Sati, Shiva's consort. Kashyap received the earth, obtained by Parashurama's conquest of King Kartavirya Arjuna and henceforth, earth came to be known as "Kashyapi".
Athri : Brahmarshi Atri is the seer of the fifth mandala (book) of the Rigveda. He had many sons, including Soma, Datta, and Durvasa, who are the incarnations of the Divine Trinity Brahma, Vishnu, and Rudra. The trimurti channeled through Brahmarsi Atri when they granted boons to his wife Devi Anusuya for helping the Sun to rise in the east everyday.
Viswamithra : Viswanithra is also credited as the author of most of Mandala 3 of the Rigveda, including the Gayatri Mantra. The Puranas mention that only 24 Rishis since antiquity have understood the whole meaning of, and thus wielded the whole power of, the Gayatri Mantra. Sage Vishvamitra is supposed to be the first, and Sage Yajnavalkya the last.
Jamadhagni: Jamadhagni was a descendant of the sage Bhrigu, one of the Prajapatis created by Brahma, the God of Creation.He has five children with wife Renuka, the youngest of whom was Parashurama, an Avatara of Lord Vishnu.
Bharadhwaja : Bharadwaja rishi was father of Dronacharya and grand father of Ashwatthama. Bharadwaja Maharshi, a sage of the Vedic period, is renowned for his thirst for knowledge. He attained extraordinary scholarship and the power of meditation.
Vashista :Vashista was the Rajguru of the Solar Dynasty. He was the mind son of Brahma. He had in his possession the divine cow Kamadhenu, and Nandini her child, who could grant anything to their owners..He is credited as the chief author of Mandala 7 of the Rigveda.