Ugrin Csák (Serbo-Croatian: Ugrin Čak or Угрин Чак; died in 1311) was a prominent Hungarian nobleman and oligarch in the early 14th century.
In the beginning of the 14th century, after the last King of Hungary from the House of Árpád on the male line died in 1301 a brief period of interregnum followed. During this period, many Hungarian nobles assumed regal rights for themselves and gained power to the point of becoming oligarchs (powerful barons) and extended their local jurisdiction and influence over large territories, with their own private armies, administration and juristic systems. Some of them felt strong enough not to accept the rule of king Charles I of Hungary over them.
Still, Ugrin Csák, although he was one of these oligarchs, is considered to have been a very determined follower of the King. He ruled over present-day region of Syrmia and parts of present-day regions of Slavonia and Bačka, and later also over part of Banat. His residences were in Újlak (Ilok) and Pozsega (Požega). After Ugrin Csák died, in 1311, the territory under his control was placed under direct control of king Charles I of Hungary. This extension of his personal territory, helped the king of the Kingdom of Hungary to defeat other local oligarchs.