Saint Christopher is one of the most popular Catholic Christian heroes of the Faith. He is a saint, indeed listed as a martyr. He may have also been named Reprobus. He apparently died under the Roman Emperor Decius, in 251 AD. Most Catholics refer to him as Saint Christopher anyway, and his medals and the popular devotions to him are among the most common in Catholic piety.
Other than his listing as a martyr, there are no primary sources referring to St. Christopher, only stories and traditions which have been passed down.
According to these accounts, St. Christopher was extremely tall, and by some accounts he was even a giant! He was surely a man of significant physical stature. But, more importantly, he was a spiritual giant and a sure model and inspiration for the Christian faithful.
Christopher decided one day that he wanted to serve the greatest king he could. He presented himself before his local ruler and entered service, until he noticed the king cross himself at the mention of the devil, revealing that the king believed the Devil to have more power.
St. Christopher then decided to serve the Devil. During his search, he encountered a band of thieves, whose leader referred to himself as the Devil. But when this leader avoided a Christian cross out of fear, St. Christopher learned there was someone even more powerful than the Devil.
St. Christopher found a hermit who taught him all about Christ, the King of Kings. The hermit suggested that he spend his life in prayer and fasting, a thing which St. Christopher, a large and probably often hungry man found difficult, he objected. The hermit suggested he then find something else that would please Christ. St. Christopher offered to work at a nearby river, and help travelers across. The fording was dangerous and many with less strength people had drowned. The hermit advised St. Christopher this would please Christ.