(The Y in this name is a consonant. It is pronounced like 'y' in 'you'.)
( The same name with the same spelling and pronunciation occurs else where too. One was -in Aadi parva- the name of a serpent chief. Another was -in Udyoga parva- the name of a notorious king among the Neepa race, mentioned by Bheema while talking to Krishna about eighteen notorious destroyers of their own races. Yet another was the ancestor of Paandavas and son of Kuru. One more was that of a king mentioned by Drupada- in Udyoga parva- while listing the kings from whom Paandavas may seek assistance in the war. In this link, presently we deal with Janamejaya who was Pareekshith's son and performer of the serpent sacrifice. See the link "Janamejaya2.html" for other names. Reader should be careful to avoid confusion. )
Janamejaya was the son of Pareekshith, grandson of Abhimanyu and great-grandson of Arjuna. His father Pareekshith was killed by a serpent Thakshaka due to a curse from sage Shringi (sage Shameeka's son). He ascended to the throne after his father, at a young age of twenty five.
At the behest of a sage Udanka, he wanted to avenge his father's killing by Thakshaka and undertook a serpent-sacrifice to kill all the serpents in the world. Vyaasa too was invited for this occassion. But, he was to drop it in the middle at the request of sage Aastheeka, a relative of the serpent lords.
Janamejaya on that occasion asked Vyaasa about the rift between the Paandavas and Kouravas . Then Vyaasa ordered Vyshampaayana to relate the Mahaabhaaratham to the king. At a point during the relating of the story, Janamejaya requested Vyaasa to show him hs late father and was granted that request.
Janamejaya was the last famous king of the Paanadavas'lineage and also the last performer of the Asvamedha sacrifice.