Ruben Lagus (October 12, 1896 - July 15, 1959) was a Finnish Major General.
Lagus was one of the Finnish Jaeger troops trained in the volunteer Royal Prussian 27th Jäger Battalion. During the Winter War he was in charge of the supplies of the troops fighting in Karelian Isthmus.
In the Continuation War he first was the commander of the Jaeger Brigade and later the Armoured Division. He was the first soldier to be awarded the Mannerheim Cross on July 22, 1941.
