Hypertrichosis is a rare genetic condition that results in extreme hairiness. It is sometimes referred to as “werewolf syndrome”. Only about 50 cases in history have been documented. There is some speculation that Esau, son of Isaac and twin brother of Jacob, may have had hypertrichosis. He was described in the Old Testament as born covered in red hair, and was referred to as a hairy man by his brother as an adult. Here are several more cases.
Petrus Gonzales

Petrus Gonzales was born in the Canary Islands around 1556 and taken to be presented to French King Henri II due to his unusual appearance. As a member of the court, he was educated and showed great intelligence. He married and produced five hairy children, three daughters and two sons. A grandchild was also reported with hypertrichosis, and possibly more descendants were affected.