Nils Middelboe was a Danish amateur track and field athlete and football player as well as a football referee and leader. He represented the Denmark national football team at the 1908, 1912 and 1920 Summer Olympics, winning silver medals in 1908 and 1912. He was the first ever goalscorer for the Denmark national football team, when he scored in Denmark's debut game at the 1908 Summer Olympics. In 1913, he moved abroad to play for English club Chelsea, and became the first foreign player to ever represent the club.

Einar Middelboe was a Danish footballer who played as a midfielder for Kjøbenhavns Boldklub. He was one of the listed players of the Danish football squad that competed in the 1908 Summer Olympics, but did not play in any of the matches at the competition. He is the brother of Kristian Middelboe and Nils Middelboe, both of which played for the Danish national team.