Which Titan was the father of the goddess Leto?

Coeus was the Titan father of the goddess Leto.

In Greek myth, Coeus was one of the twelve Titans born to Uranus and Gaia. He was paired with his sister Phoebe, a Titaness associated in later tradition with prophetic or intellectual qualities. Their children were Leto and Asteria, making Coeus the grandfather of Apollo and Artemis through Leto.

Leto later became the consort of Zeus and the mother of the divine twins Apollo and Artemis. Hera’s hostility toward Leto forms part of the background to the twins’ unusual births: according to later myth, Leto struggled to find a place where she could safely give birth, eventually reaching the island of Delos.

A common mix-up is to name Phoebe, because she was Leto’s mother, not her father. Coeus himself has few independent myths and is known mainly through genealogical passages in ancient literature, especially Hesiod’s Theogony. His importance comes largely from his place in the ancestry of major Olympian gods.