|Full name||Eulogio Aranguren Labairu|
|Date of birth||July 27, 1892|
|Place of birth||Buenos Aires, Argentina|
|Date of death||1973|
Eulogio Aranguren Labairu (born 27 July 1892 in Buenos Aires, Argentina), is a former Spanish footballer who spend his youth in Basque Country. He was a midfielder and played the most of his career for Real Madrid C.F.. He was the elder brother of Sotero Aranguren with whom he was team-mate at Real Madrid.
He played for Real Madrid for 10 years, between 1911 and 1921. In this period he made 20 appearances but failed to score in official games, as he played mostly as defender.
Three years after the premature death of his brother, together with King Alfonso XIII and a sister of Machimbarrena (captain of Real Madrid who also died in the same period), inaugurated the famous statue at the entrance of the first team's locker room. This statue is seen as a talisman for club's next generations of footballers.
In 1925 he founded the Real Madrid rugby team, the next years he was a referee and after that became president of the Castilla Referee Federation.
He also was vice president of the Spanish Football Federation, and in several occasions joined the Spanish national football team as official. He studied to became a lawyer. He had 5 children, Jose Eulogio (Josechu), Maruchi, Fernando, Sotero (died when child) and Ignacio.
Together with his brother, they were the firsts Argentine born footballers who played for Real Madrid.