William Marshall "Big Bill" Hollenback (February 22, 1886 – March 12, 1968) was an American college football player and coach.

He played football at the University of Pennsylvania, where he was selected as an All-American fullback three straight years, from 1906 to 1908.

Jim Thorpe, whose Carlisle Indians team played Penn to a 6–6 tie in 1908, called Hollenback his "greatest and toughest opponent."

In 1925, Hollenback served as the referee for the Pottsville Maroons' 9–7 victory over the Notre Dame All-Stars, featuring the legendary Four Horsemen, at Shibe Park.

The game resulted in a controversy that stripped the Maroons of their 1925 NFL championship Hollenback received a degree in dentistry, but opted to become a football coach after graduating from Penn.