Cotys I or Kotys I (Ancient Greek, "??t??") was born during the reign of Seuthes I. He became king after he killed the previous Thracian king Hebryzelmis. On gaining the Odrysian kingdom the Athenians made him their ally. In order to make his position stronger Cotys married his daughter to the Athenian general Iphicrates who soon became the second person in command after the king. Cotys assisted the Hales, leader of Triballi, a powerful Thracian tribe of Moesia, against Abdera. In 375 BC the Triballi, rebelled against his kingdom. One of the reasons for this revolt was that the Triballi were unable to get luxurious goods and other items from the south. Cotys stopped the rebellion by rebuilding the Greek city of Pistiros.
On the revolt of Ariobarzanes of Phrygia from Persia, Cotys opposed him and his ally, the Athenians. Soon after, he went to war with the Athenians for the possession of the Thracian Chersonese. Now that Athens could not trust Iphicrates to protect her interests, she organized a rebellion against Cotys, led by his treasurer Miltokythes. Yet Iphicrates, with the help of Charidemus, bribed the Athenian military and naval commanders to suppress the rebellion. In 361 BC, Charidemus returned to Athens with a treaty from Cotys, proclaiming him an ally. Cotys had successful retained his kingdom.
By 359 BC, Cotys controlled the whole Chersonese peninsula. During the same year he made an alliance with the new Macedonian king, Philip II. In 358 BC, he was murdered by two of Platos students from Aenus, Python and Heraclides. Thought previously as advisers to the King, they murdered him during a feast in his palace, under the pretext that he had wronged their father. Upon their return to Athens, they were proclaimed honorary citizens and rewarded with gold wreaths.
Kotis Point on Livingston Island in the South Shetland Islands, Antarctica is named after Cotys I.
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