Mikhailo Olelkovich

Mikhailo or Mikhail Olelkovich (; died August 30, 1481) was a noble from the Olelkovich family of the Grand Duchy of Lithuania who served as the appanage prince of Kopyl and Slutsk.

Novgorod affair

According to the 1456 Treaty of Yazhelbitsy, the Novgorod Republic became dependent on the Grand Principality of Moscow and was not allowed to conduct an independent foreign policy.

Moscow accused Novgorod not only of violating the treaty, but also of religious treachery; there were also allegations that the marriage would have brought Novgorod over to Catholicism, but Gail Lenhoff and Janet Martin argue that the pro-Lithuanian, pro-Catholic allegations are highly suspect and, indeed, very unlikely. Mikhailo was an Orthodox Christian (as was Marfa Boretskaya), and he and his brother had strong differences of opinion with Casimir IV Jagiellon.

Mikhailo entered Novgorod on November 8, 1470 with a large retinue, and remained in the city until March 15, 1471. His large retinue included a certain Skhariya, who gained a following in Novgorod. The heresy spread from there to Moscow in 1479, when the grand prince Ivan III transferred several heretical priests to Moscow. The affair ended when Mikhailo withdrew from the city and Ivan III defeated the Novgorodians at the Battle of Shelon in July 1471. Robert O. Crummey says that Mikhailo was of "impeccably Russian and Orthodox background", but quickly became disillusioned with the new office and plundered the southern territories of the republic as he left. Feodor managed to escape to the Moscow grand principality.