Severyn (Semeriy) Nalyvaiko (Ukrainian: ??????? (???????) ?????????, Polish: Seweryn Nalewajko, in older historiography also Semen Nalewajko, died 21 April 1597) was a leader of the Ukrainian Cossacks who became a hero of Ukrainian folklore.
He led the failed Nalyvaiko Uprising for which he was tortured and executed in Warsaw.
The Decembrist poet Kondraty Ryleyev wrote a poem about him.