is an English professional footballer who plays for Women's Super League club Arsenal and captains the England women's national team. A versatile player, she plays in central defence or the midfield. She has spent her entire senior domestic career at Arsenal. She also represented Great Britain at the Olympics in 2021. Williamson captained England to their first UEFA European Championship victory, and the women's team's first international title, in 2022, for which she was named in the Team of the Tournament.

After being part of Arsenal's youth programme from the age of nine, Williamson debuted for the senior team as a teenager at the end of their 2014 Champions League campaign; she started for them in the League Cup final that year, in which she had individual success. With Arsenal, Williamson has won the League and Champions League once and the FA Cup and League Cup twice each. She has captained Arsenal on various occasions and reached 200 appearances for them in December 2022.

Williamson represented England for all their age-group teams before making her senior debut in 2018, for 2019 FIFA World Cup qualifying. She was used sparsely in her first years with England, then became a regular under manager Sarina Wiegman, who also made her permanent captain in 2022.