Antonina Jadwiga "Nina" Siemaszko (born July 14, 1970) is an American film and television actress.
Siemaszko was born in Chicago. Her father, Konstanty, was a Polish-born Roman Catholic who was a fighter in the Polish Underground, and who survived the Sachsenhausen concentration camp, Her mother, Collette McAllister, was English. Her brothers are Casey Siemaszko, an actor, and Corky Siemaszko, a reporter and writer for the New York Daily News. She attended the Goodman School of Drama at DePaul University in Chicago, which her brother Casey also attended.