William Irwin Schaffer (February 11, 1867 – January 15, 1953) was an American lawyer and judge from Pennsylvania.

He was active in Republican politics, and was appointed by Governor William Cameron Sproul, first as Attorney General, and then to fill a vacancy on the state Supreme Court.

[3] He is buried at West Laurel Hill Cemetery in Bala Cynwyd, Hanover Section, Lot 26.

Schaffer wrote the majority opinion in the 1927 case deciding that Sunday baseball was in violation of the state's 1794 "blue laws".

[4] Schaffer was identified, along with Justice John W. Kephart, in a Senate Banking Committee investigation, as being on a J.P. Morgan & Co. "preferred" list, allowing them steeply discounted prices for the purchase of certain securities.