William Thomas Granahan (July 26, 1895 – May 25, 1956) was a Democratic politician from the U.S. state of Pennsylvania, most prominently serving in the U.S. House of Representatives from 1945–47 and 1949-56.

[1] He attended parochial schools and La Salle Extension University in Chicago, Illinois.

In the late 1930s, he entered the world of Democratic politics, serving as a member of the state party committee from 1938-42.

After being sent to Congress in the 1944 elections, he lost a bid for reelection, defeated by Republican Robert N. McGarvey.

However, he took back the seat from Congressman McGarvey two years later, and went on to serve four more terms until dying from a heart seizure following a minor abdominal surgery at Fitzgerald Mercy Hospital in Darby, Pennsylvania.