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.

The following teams took part at the 1908 Summer Olympics: