William Parsons Alexander (19 January 1877 – Unknown) was an Anglo-Spanish footballer who is best known for being, along with his brother John, one of the founders of FC Barcelona in 1899, and then serving as the club's vice-captain in 1899 and 1900.

[8] Despite some encouraging first steps, this society was never officially established and when its founder and captain James Reeves returned to the United Kingdom in the autumn of 1895, it was the Catalans and the Parsons brothers who took the reins of the team, but without Reeves, the entity soon declined, collapsed and seems to disappear around 1896.

[8][1] In 1899, Parsons and his brother were among the twelve men who attended the infamous meeting held at the Gimnasio Solé on 29 November 1899 which saw the birth of Foot-Ball Club Barcelona.

[9][10] However, in Barcelona's official debut on 8 December 1899, the two Parsons brothers played for the rival team, Team Anglès, which consisted of members of the British colony living in Barcelona, such as the two of them and the Witty brothers (Arthur and Ernest), helping Anglès to a 1–0 win.

[2][3][12] However, he never managed to defend that responsibility on the playing field because in February 1900, he left for Manila for family reasons, leaving the vice-captaincy of Barcelona in the hands of Ernest Witty.