William Dagger (born 21 February 1999)[2] is an English professional rugby league footballer who plays fullback, wing, centre, stand-off, scrum-half for York Knights in the RFL Championship.

Dagger has spent time on loan from Hull KR at the York City Knights in League 1, and at the Leigh Centurions and Featherstone Rovers in the Championship.

[9] It was revealed on 26 July 2018, that Dagger would spend the remainder of the 2018 rugby league season at the Leigh Centurions, on a loan basis from his parent-club Hull Kingston Rovers.

[13] In round 18 of the 2023 Super League season, Dagger kicked a drop goal in golden point extra-time which gave Wakefield Trinity a 27-26 upset victory over Wigan.

[14] Dagger played 16 matches for Wakefield Trinity in the Super League XXVIII season as the club finished bottom of the table and were relegated to the RFL Championship which ended their 24-year stay in the top flight.