His name was Saint Christopher, and legend holds that he was a dog-faced man.
Venerated in the Catholic Church, the man who would one day become a saint was purported to have the head of a dog--a member of a race of giants who ate human flesh. During his time, it was accepted that several races existed in the world, including the Chananeans, a dog-headed people.
The German Bishop (and poet) Walter of Speyer told the story of how Christopher met the Christ child and regretted his former ways, accepting Baptism and receiving a human appearance. Christopher then devoted his life to Christian service, eventually becoming a Saint.
Does this mean there actually were a race of Dog-headed people in the world?
There was a widespread belief in cynocephaly (having the head of a dog or jackal) in the ancient world--and not just Anubis. The Greek physician Ctesias wrote in the 5th Century BC of cynocephali in India--the Indica. The Greek traveler Megasthenes also report a dog-headed people in India who lived in the mountains--barking and wearing the skins of wild animals. Herodotus reported claims from ancient Libyans of similar creatures inhabiting their eastern lands. The Buddhist missionary Huisheng described an island of dog-headed east of Fusang. Li Yanshou, a Tang dynasty historian, also spoke of a 'dog kingdom'.
These are but a few of the historical accounts of dog-headed men. There is also the legend of werewolves. And then there's hypertrichosis: a condition that causes hair to grow from the face--all of the face. Sufferers aren't just footnotes in circus history: people today still suffer from the condition that could indeed cause one to be mistaken for an animal.