Mackenzie Elizabeth Arnold is an Australian professional soccer player. She plays as a goalkeeper for Women's Super League club West Ham United, where she is team captain, and for the Australia national team. She previously played for Arna-Bjørnar in Norway's Toppserien as well as Brisbane Roar, Perth Glory, Western Sydney Wanderers, and Canberra United in Australia's W-League.

West Ham United Women Football Club is an English women's football club affiliated with West Ham United. The club plays in the Women's Super League, the top tier of English women's football. They were formed in 1991 and play home games at Dagenham & Redbridge's Chigwell Construction Stadium on Victoria Road.