Milko Kos (12 December 1892 – 24 March 1972) was a Slovenian historian, considered the father of the Ljubljana school of historiography.

He was born in the town of Gorizia (then part of Austro-Hungarian Empire, now in Italy), where his father, the renowned medievalist Franc Kos, taught at the state high school.

In this position, he influenced almost all Slovenian historians of the post–World War II period; most of them graduated under his direct supervision, including Fran Zwitter and Bogo Grafenauer.

During the difficult period of Italian and Nazi German annexation of Slovenia, Kos maintained an underground connection with the Liberation Front of the Slovenian People.

In 1955, he received the Prešeren Award, the highest recognition for cultural achievements in Slovenia, for his work on the land registers in the Slovenian Littoral.