Father Simon

Father Simon was the local priest of Alimango Island. He was the one who taught Shirley to read and write due to a lack of a school on the island. After Norikata Emiya and Kiritsugu Emiya arrived on the island, he became vary wary of Norikata for the following year.

[Spoiler] Simon contacts people off the island for help, leading to the Holy Church and Mage's Association to exterminate the island, and goes to warn the villagers. Simon is turned into a ghoul while warning the villagers, later killed by Natalia Kaminski while he is about to attack Kiritsugu. [/Spoiler]

(Source: TYPE-MOON Wiki)