William "Billy" Wallis (born c. 1877, died c. 1957) was an English international rugby union player who represented his country on four occasions between 1900 and 1903. He played primarily as a forward, a position encompassing roles such as lock or flanker in the modern game.
Early Life and Club Career Wallis's rugby career began in the late 19th century. He was notably associated with Cambridge University RFC during his time studying there, earning a Blue for his participation in the Varsity Match. After his university tenure, he played for Northumberland, a prominent county club in English rugby at the time.
International Career Wallis made his debut for the England national team on 6 January 1900, in a match against Wales at Kingsholm, Gloucester, as part of the Home Nations Championship. He also featured in England's subsequent match against Scotland that year.
He returned to the international stage in 1902, playing against Wales once more. His final cap for England came on 21 March 1903, in the Calcutta Cup match against Scotland at Richmond, London, during the 1903 Home Nations Championship. Over his four international appearances, Wallis contributed to England's efforts in the forward pack during a period of significant development in the sport.