Christopher I (Danish: Christoffer I) was King of Denmark between 1252 and 1259. He was the son of Valdemar II of Denmark by his wife, Infanta Berengária of Portugal. He succeeded his brothers Eric IV Plovpenning and Abel of Denmark on the throne. Christopher was elected King upon the death of his older brother Abel in the summer of 1252. He was crowned at Lund Cathedral on Christmas Day 1252.
Christopher tried to have his brother Eric IV canonized, but without Archbishop Jacobs' support it came to naught. When Duke Valdemar died, King Christopher tried to prevent Valdemar's brother, Eric Abelsøn, from taking the duke's place. Valdemar's widow encouraged a few counts of northern Germany to rebel. In the confusion, Christopher fled to Southern Jutland to stay with the Bishop of Ribe.
The King died "unexpectedly" after taking Holy Communion. According to contemporary sources, King Christopher died after drinking poisoned communion wine from the hands of abbot Arnfast of Ryd Abbey in revenge for his mistreatment of Archbishop Erlendsen and the king's oppression of the church. King Christopher's excommunication had no effect, and he was buried in front of the high altar of Ribe Cathedral immediately after his death on 29 May 1259. The king may have died of natural causes; Christopher's allies, however, called him Krist-Offer ("Christ's sacrifice"). Christopher was succeeded by his son Eric, as Eric V of Denmark.