Who was Lot's father?

Answer: Haran

Terah was the father of Abram, Nahor and Haran. Haran, the father of Lot, died in Ur of the Chaldeans before Terah.

“This is the account of Terah. Terah became the father of Abram, Nahor, and Haran. And Haran became the father of Lot. During his father Terah’s lifetime, Haran died in his native land, in Ur of the Chaldeans.”— Genesis 11:27-28 (BSB)