King Puru was a Puranic king and the youngest son of king Yayati and Sharmishtha and one of ancestors of the Pandavas and Kauravas.
In the nineteenth chapter of book nine of the Bhagavata Purana, Puru is described as having four brothers; Yadu, Turvasu, Druhyu and Anu. He exchanges his youth for old age of his father Yayati when Yayati gets cursed by Shukracharya. In return Yayati makes him his descendant though he was youngest of all. His son and successor is named as his son was Práchinvat; his son was Pravíra; his son was Manasyu.
In the Mahabharata - Adi Parva, he is said to have inherited his kingdom in the Gangatic plain. He is said to have three mighty heroes as sons by his wife Paushti; Pravira, and Raudraswa. Pravira succeeded Puru and was in turn succeeded by his son Manasyu.
Puru ruled from the centre as a supreme World Emperor or King of Kings. This also showed his supreme power and displays the right of people named Puru. His dynasty becomes the Puru vamsha which was later renamed as Kuru Vamsha to which Pandavas and Kauravas belong.
Another Puru is mentioned as a king in the Rigveda and as the father of Adityas, married to Aditi, living and ruling over and area of the Saraswati river.
A King Puru is also mentioned in Korean mythology as the son of a heavenly king called Haemosu who ruled the Buyeo kingdom. The Korean King Puru went on to succeed his divine father and ruled in peace and prosperity. There is a story that when he grew old in age without any children, he was led to a large stone by a horse. When the horse began to cry in front of the stone, the king had it moved and found a frog bathed in a golden light. The frog quickly turned into a handsome boy, which Puru interpreted as a sign from heaven and made him crown prince.