Pat Marcy (born Pasqualino Marciano, September 6, 1913 – March 13, 1993) was an Italian-American political boss who wielded enormous power over the Illinois Democratic Party during much of the 20th century.

According to Federal prosecutors, as well as informants Robert Cooley and Michael J. Corbitt, he was also a trusted and valued associate of the Chicago Outfit and the American Mafia.

Alderman Fred Roti and Democratic Committeeman John D'Arco, Sr., both of whom also had close ties to the Chicago Outfit, took direct orders from Marcy.

Marcy regularly met with the mob's main enforcers at Counsellors Row restaurant, across the street from Chicago City Hall.

According to Corbitt, Marcy was so trusted by the Outfit that money skimmed from casinos in Central America and Las Vegas was delivered directly to him.