Michael Joseph Stack (September 29, 1888 – December 14, 1960) was a U.S. Representative from Pennsylvania from 1935 to 1939.

His grandson is former Pennsylvania Lieutenant Governor Michael J. Stack III.

Stack was born in Listowel in County Kerry on the island of Ireland (the entirety of which was then part of the U.K.).

He attended St. Josephs College in Philadelphia and graduated from St. Mary's University in Baltimore, Maryland, in 1910.

During the First World War, he enlisted on July 17, 1917, as a private in the Medical Detachment, Three Hundred and Sixtieth Infantry.