Shantanu is a king of Hastinapura in the great epic of the Mahabharata.

He is father to Bhishma by the goddess of the river Ganga. After Bhishma's birth, Ganga leaves him.

When Bhishma has grown into a young handsome prince, Santanu comes across Satyavati, a ferryman's daughter, and falls in love with her. The ferryman agrees to the marriage on condition that any children Satyavati bears him would inherit the throne. King Santanu is unable to give his word as it would be unfair to Bhishma, the rightful heir to the throne. However, Bhishma comes to know of this and gives his word to the ferryman that he will leave the throne for Satyavati's child. To reassure further, he also pledges bachelorhood to ensure that future generations are also not challenged by offsprings.

Santanu and Satyavati have two sons, Chitrangada and Vichitravirya. After Santanu's death, Satyavati continues to rule the kingdom with his three sons.