The son of Krtavirya was Arjuna
Srimad-Bhagavatam
SB Canto 9
The son of Kṛtavīrya was Arjuna. He (Kārtavīryārjuna) became the emperor of the entire world, consisting of seven islands, and received mystic power from Dattātreya, the incarnation of the Supreme Personality of Godhead. Thus he obtained the mystic perfections known as aṣṭa-siddhi.
SB 9.23.24, Translation: The son of Kṛtavīrya was Arjuna. He (Kārtavīryārjuna) became the emperor of the entire world, consisting of seven islands, and received mystic power from Dattātreya, the incarnation of the Supreme Personality of Godhead. Thus he obtained the mystic perfections known as aṣṭa-siddhi.