St. Christopher was a man of large stature and great strength who made it his mission to serve Jesus. He is said to have provided aide to many travelers who needed to cross a dangerous river. One of the travelers was a child who needed to be carried across the river but as they went the child seemed to get heavier and heavier. Christopher asked why he was so heavy and it turned out the child was actually Jesus. He responded that the reason was he carried the weight of the world.
Jesus baptized him and named him and named him Christopher which means Christ Bearer. He helped spread Christianity and was martyred in 251 AD.
There is some confusion about the status of his saint designation. Hopefully this will help clarify. "During the 1960s, the Catholic Church reviewed and revised the Calendar of Saints, and eliminated the feast days of several saints including the celebration of St. Christopher which was on July 25th. Although Christopher does remain a saint, his day of celebration, July 25, is no longer listed on the Catholic calendar."