Who is Dr. Iannis from Corelli's Mandolin and what is their importance?

Dr. Iannis is the ony doctor on the island of Cephallonia. He is a widower, who lives with his daughter, Pelagia, who has raised to be an intelligent and independent young woman. He cares for his fellow villagers, accepting favors or food as payment for his services.

Iannis is an educated man and has traveled widely. He is also writing a proposed history of the island of Cephallonia. Dr. Iannis dies in 1953, when a devastating earthquake strikes the island and demolishes his house, crushing him.