Hayden Kai Muller (born 7 February 2002) is an English footballer who plays for National League club Sutton United.
Muller made his professional debut for Millwall on the final day of the 2019âÂÂ20 season in a 4âÂÂ1 victory against Huddersfield Town. He signed a new contract with the club in June 2021.
On 30 June 2021, Muller joined Scottish Premiership side St Johnstone on a season-long loan deal. He was recalled by Millwall in January 2022.
On 13 January 2023, Muller signed a multi-year contract with League of Ireland Premier Division club Dundalk.
On 9 July 2024, Dundalk announced that Muller had left the club to sign for National League side Sutton United.