Christopher I (Danish: Christoffer I) (1219 – 29 May 1259) 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 began organizing the effort to have his brother Erik IV Plovpenning canonized, laying his murder directly at the feet of his other brother Abel of Denmark. If recognized by the pope, the murder would exclude Abel's sons from the succession and guarantee Christopher's own sons Denmark's crown. This meant that Christopher as a younger son tried to keep the sons of his older brothers from ruling Denmark, which went against prevailing customs.

The king spent most of his reign fighting his many opponents. By allowing Abel's son, Valdemar Abelsøn, to be Duke of Schleswig he prevented an all-out civil war, but became the target of intrigue and treachery. Southern Jutland including Schleswig and Holstein were independent from the king's rule for a time. Christopher also gained a ferocious enemy in the newly named Archbishop of Lund, Jacob Erlandsen, who was closely connected with Abel's family. Erlandsen asserted his rights often at odds with the king. King Christopher insisted that the church pay taxes like any other land owner. Bishop Jacob refused and went so far as to forbid peasants who lived or worked on church properties to give military service to King Christopher. Erlandsen was perhaps the wealthiest man in the kingdom and insisted that the secular government have no control or hold over the church, its property, or ecclesiastical personnel. He simply excommunicated the king to show that he wasn't about to surrender to the king's will.

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