|Parents||Ruchika (Descendent of Sage Brighu, son of Bramha)|
|Children||Vasu, Viswa Vasu, Brihudyanu, Brutwakanwa and Parashurama|
According to Hindu legends, Jamadagni (or Jamdagni, Sanskrit: ?; Pali: Yamataggi) is one of the Saptarishis (Seven Great Sages Rishi) in the seventh, current Manvantara. He is the father of Parashurama, the sixth incarnation of Vishnu. He was a descendant of the sage Bhrigu, one of the Prajapatis created by Brahma, the God of Creation. Jamadagni had five children with wife Renuka, the youngest of whom was Parashurama, an avatar of Lord Vishnu. Jamadagni was well versed in the scriptures and weaponry without formal instruction.
Lineage: Even today it is believed that we have descendents from Jamadagni's family tree. In fact other than being one of the saptharshis, Jamadagnis name is still in vogue with some families, particularly around south india carry Jamadagni Gotra. Originally, it is briefed (source: Bhaagavatha purana) that Sage Bhrigu is the earliest predeccessor to Jamadagni's family tree.
Bhrigu -> Chyavana -> Aaplavana -> Aurava -> Ruchika (Jamadagni's father)
According to the Bhaagavata Purana, sage Richika was asked by King Gadhi to bring thousand white horses with black ears to marry Satyavati. Richika with the help of Varuna brought those horses and the king allowed Richika to marry Satyavati.
After their marriage, Satyavati and her mother demanded from Richika the blessings for having a son. In accordance the sage prepared two portions of milk boiled rice for each, one with Brahma mantra (for Satyavati) and other with Kshaatra mantra (for his mother in law). Giving the respective portions, he went to perform his ablutions. Meanwhile, Satyavati's mother asked her daughter to take her portion and give Satyavati's to her. Her daughter followed her order. When Richika came to know about this exchange he said that the child born of his mother in law would be a great Brahmana, but his son would become an aggressive warrior who will bring bloodbath to this world. Satyavati prayed that her son would remain a calm sage but her grandson should be such an angry warrior. This results in Jamadagni being born as a sage (out of Satyavati's womb) and eventually, PrasashuRama being born as Jamadagni's son with a fearful reputation.
Thus Jamadagni was born from Satyavati who became a sage and one of the 7 great rishis (Saptharshis). Meanwhile, around the same time as Jamadagni's birth - Gadhi's wife (Satyavati's mother, whose name is not mentioned) gave birth to a son with Kshatriya traits names Kaushika. He later becomes world renowned "Vishwamitra", who was Kshatriya by birth but later ascended to the status of a Brahmarishi. 
Jamadagni had 5 sons from Renuka devi, of which Rama (ParashuRama) is arguably the most famous and known character. Parashurama is often accredited to be angry, reckless and anti-kshatriya. This perception is a common fallout due to stereotyping people. According to puranas and upanishats, ParashuRama's birth was destined to be an incarnation of Lord MahaVishnu - with a purpose of cleaning up the earth from autocracy, misgovernance, dictatorship and bad rule. The event of Kartiveeryarjuna describes in detail about how the 21 rounds of ParashuRama started.
Until Renuka Devi's beheading episode, Jamadagni is often projected to be impulsive and anger driven. But eventually, ParashuRama was granted 3 boons by Jamadagni after beheading Renuka, for which he prayed for the following wishes - 1) To bring all his brothers back to life, with memories of the past, except the beheading episode; 2) Bring Renuka Devi back to life; 3) Jamadagni should relinquish anger and use his knowledge for the betterment of mankind.
A descendant of sage Bhrigu, Jamadagni literally meaning consuming fire. Vitahavya was a king but became Brahma?a under the influence of Bhrigus. His son, Saryati, was a great king. The Mahabharata refers to King Saryati as one of the greatest kings (24 kings) of the pre-Mahabharata. Chyavana was the contemporary of King Ku?an?bha. They had a son called Urva. Rishi Richika was born to Aurava, a son of Urva, and he married Satyavat?, sister of King G?dhi. Jamadagni was born to Rich?ka and Satyavati, daughter of Kshatriyariya king Gaadhi. Growing up he studied hard and achieved erudition on the Veda. He acquired the science of weapons without any formal instruction. His father, Richika had guided him though. The Aushanasa Dhanurveda which is now lost, is about a conversation between Jamadagni and Ushanas or Shukracharya on the exercises of warfare. Rishi Jamdagni went to King Prasenjit, of solar dynasty or Suryavansha, and asked for his daughter Renuka's hand in marriage. Subsequently, they (Jamdagni and Renuka Mata) were married, and the couple had five sons Vasu, Viswa Vasu, Brihudyanu, Brutwakanwa and Bhadrarama, later known as Parshurama.
According to the Mahabharat, Jamadagni once became annoyed with the sun god Surya for making too much heat. The warrior-sage shot several arrows into the sky, terrifying Surya. Surya then appeared before the rishi as a Brahmin and gave him two inventions that helped mankind deal with his heat - sandals and an umbrella. 
Renuka was a devoted wife. So powerful was her chastity, that she used to fetch water from the river in a pot made of unbaked clay every day, held together only by the power of her devotion to Jamadagni.
One day while at the river, a group of Gandharvas passed by in the sky above in a chariot. Filled with desire for only a moment, the unbaked pot that she was carrying dissolved into the river. Afraid to go back to her husband, she waited at the river bank.
Meanwhile, Jamadagni noticed that his wife had not yet returned from the river. Through his yogic powers, he divined all that had taken place and was filled with rage. Jamadagni called his eldest son, told him what had happened, and asked him to execute his mother. Horror-stricken, his son refused to perform this deed. He then asked all of his sons, and as they refused, he turned them one by one to stone. Finally, only his youngest son, Parashurama, was left. Ever-obedient and righteous, Parashurama went to behead his mother[further explanation needed]. Renuka was then hiding with a fisherman and his wife. To complete the deed, Parashurama killed the brave fisherman who went to fight him. After that, he beheaded the wife and then Renuka[clarification needed].
Pleased, Jamadagni offered two boons to Parashurama. Parashurama asked that his mother be restored to life and his brothers to be turned from stone back to flesh. Impressed by his son's devotion and affection, Jamadagni granted the boons. His brothers were reformed from stone without having the memory of experiencing death as an additional wish of Parashurama. With the holy water, Parashurama bound the head of the fisherman back to the fisherman's body. Excited at seeing how it had succeeded, he bound the women's heads to their bodies. After they ere resurrected, he had noticed that he had switched the bodies. Now both women were unchaste as the fact that their body or head would have had to been unchaste for the other to be chaste. Jamdagni then blessed them to be called goddesses. Thus we know her as Renuka Devi, and her assistant - companion, the fisherman's wife. The purpose of this trial was to demonstrate the dharma ("rightful duty") of a son towards his father.
The Sampangirama family is the eldest of the many families that contains the decedents of Jamadagni. The Sampangirama family goes by many last names, the most notable being Sampangirama, Nagar, and Rao. The Sampangirama family follows the pravara (bloodline): Bhargava, Chyavana, Apnavana, Aurva, Jamadagni, Parashurama. Majority of the Sampangirama family lives in the state of Karnataka.
Another notable mention is of a small, but recently discovered families of Terakanambi, Kotthalavadi, Beratahalli, Belakuppe and other surrounding places. Again set in the south Indian region between the borders of Karnataka and Tamil Nadu. Their pravara is also uniquely set with 5 rishis (Pancharishi) of Bhargava, Chyavana, Aplavana, Ourava and Jamadagni. Even today, a majority of these families reside around Mysore, Bangalore and Chamarajanagar districts in Karnataka. It is important to note that upakarma rituals for this gotra is elaborate and lengthier than their 3 rishi (Triyarishi) counter parts, as it involves extra homas, tarpana and rishi poojas.
Jamadagni was later visited by the Haihaya king Kartavirya Arjuna (who was said to have thousand arms/hands), who he served a feast using a divine cow called Kamdhenu. Wanting the Divine Cow "Kamdhenu" for himself, the king offered wealth to Jamadagni which he refused. Then the king forcefully took the Kamdhenu with him asking Jamadagni to take it back if possible, but by the means of war, which Jamadagni was not willing to.
Knowing this fact and enraged, Parashurama killed the king, and retrieved the Kamdhenu by killing all of the army of the king Kartavirya Arjuna by himself alone. Later, three sons of the king killed Jamdagni because he was the father of Parashurama who had killed their father, that felt them the proper revenge of eye-for-an-eye. They first stabbed Jamdagni twenty-one times and then sliced his head.
Again enraged, Parashurama killed all three brothers and retrieved the head of his father for cremation, and ultimately enacted a genocide on the kshatriya caste throughout the world for the next twenty-one generations since his mother beat her chest twenty-one times resembling a low-born in mourning after his father was stabbed by the miscreants.
In the Buddhist Vinaya Pitaka section of the Mahavagga (I.245) the Buddha pays respect to Jamadagni by declaring that the Vedas ( Shruti's) in their true form were revealed to the original Vedic rishis, including Jamadagni.