Vasudeva, father of Sri Krishna, was the son of Sura and Marisa of the celebrated Yadava clan. He had a sister, Pritha, better known as Kunti later on.
He was married to Devaki, daughter of Devaka, born in the equally illustrious Mahabhoja lineage. Kamsa, Devaki's brother, acting as charioteer of her marriage chariot, heard an aerial voice – "O arrogant one, Devaki's eighth issue has been destined as your slayer!"
Kamsa, filled with fury and fear, rushed to Devaki to kill her in order to prevent the prophecy from becoming true.
Vasudeva, however, intervened and implored him to spare Devaki but on the condition that all her infants, as and when born, would be immediately handed over to him. Kamsa reluctantly accepted the entreaties of Vasudeva, but imprisoned and fettered them both.
Accordingly, Kamsa killed the six first born children of Devaki and Vasudeva. The seventh was Balarama who was transferred to the womb of Rohini in Gokul.
When Krishna was about to be born to evade Kamsa killing him, the devas inspired and enabled Vasudeva to accomplish the exchange of Krishna with Yashoda's new born child in Gokul.
Krishna grew up and killed Kamsa and freed his parents Vasudeva and Devaki.
A fun fact is that Sri Krishna is also called Vasudeva.