William Dagger (born 21 February 1999) is an English professional rugby league footballer who plays as a fullback or on the wing for Wakefield Trinity in the Betfred Super League.
He primarily plays as a fullback, but he can also play on the wing, he has also occasionally featured as a stand-off and scrum-half. In 2017, he made his début for the Warrington Wolves against the Castleford Tigers. In October 2017, Dagger signed a three-year contract to play for Hull Kingston Rovers in the Super League.