Frank Winterstein (born 17 December 1986) is an Australian international rugby league footballer who plays as a second-row forward for Toulouse Olympique in the Betfred Championship. Winterstein previously played for the Canterbury-Bankstown Bulldogs, Manly-Warringah Sea Eagles and the Penrith Panthers in the National Rugby League (NRL), and for the Wakefield Trinity Wildcats, Crusaders Rugby League and the Widnes Vikings in the Super League. He played rugby union for the Kintetsu Liners in the Top League and the Australian rugby sevens team.