Krzysztof Kosiński,[1] also known as Kryshtof Kosynsky[2] (uk|Криштоф Косинський, Kryshtof Kosynsky; pl|Krzysztof Kosiński; 1545–1593), was a Cossack noble from the Podlachia region. He was a colonel of the Registered Cossacks and self-proclaimed hetman. He led two consecutive rebellions against the local Ruthenian nobility, known as the Kosiński uprising.
The Kosiński uprising (1591–1593) is a name applied to two rebellions in the eastern parts of the Polish–Lithuanian Commonwealth (modern-day Ukraine) organised by Krzysztof Kosiński against the local Ruthenian nobility and magnates.
His forces were first defeated by Duke Janusz Ostrogski in the Battle of Piątek on 2 February 1593. Kosiński promised to subject his forces to the Polish Monarchy; however, he soon escaped to Zaporizhzhia, where he began organizing a new army. In 1593 he set out for Cherkasy but was soon killed.