Timna, a concubine of Eliphaz, bore Amalek. Amalek was a grandson of whom?

Answer: Esau

Timna, a concubine of Esau's son Eliphaz, gave birth to Amalek; these were grandsons of Esau's wife Adah.

“Additionally, Timna, a concubine of Esau’s son Eliphaz, gave birth to Amalek. These are the grandsons of Esau’s wife Adah.”— Genesis 36:12 (BSB)