Isaak Boretsky

Isaak Andreyevich Boretsky (; died after 1456) was a Russian nobleman who served as a posadnik (mayor) of Novgorod in the 15th century.

Life Isaak Boretsky was born into a noble family descended from , according to the historian Valentin Yanin. The family owned the volost (rural district) of Borok, from which it derived its surname. He is first mentioned in 1417 defending that volost from raiders who had arrived from Vyatka and Ustyug.

He was elected as posadnik (mayor) of Novgorod sometime before 1428. A treaty was signed in 1439, according to which Boretsky forbade German merchants from leaving Novgorod until Russian merchants were returned from Dorpat and Reval. As a result of tensions with the Hanseatic League, the Novgorodian authorities feared that releasing foreign merchants prematurely would lead to the arrest of more Russian merchants.

In 1453, Boretsky had a secret conversation with the deacon Stefan Bradaty, a confidant of Grand Prince Vasily II who had arrived from Moscow. Stefan brought poison to Boretsky, who then bribed one of Dmitry Shemyaka's cooks to put it in his food. As a result, Dmitry died a few days later.

He is last mentioned in a 1456 charter by Vasily II addressed to Novgorodian governors, which refers to complaints by his peasants from Ustyug about goods taken from them on the Dvina by the stewards of the boyars Mikhail Tucha and Isaak Boretsky. Vasily II insisted that those who had suffered "from robbery" be compensated, and likely soon after this, Boretsky died. Yanin believed he died in the 1460s.

Family He married Marfa. It is not known when they married. Together, they had two sons: Dmitry and Fyodor. Dmitry later became posadnik in February 1471.