The Blue Lions house at the Officers Academy is comprised of students who hail from the Holy Kingdom of Faerghus. As their homeland is known for its knights, many of the students are proficient at using spears.
The Blue Lions were named after the founder of Faerghus, Loog, the King of Lions, who had a penchant for blue.
- Dimitri Alexandre Blaiddyd - The noble Prince of the Holy Kingdom of Faerghus and the house leader of the Blue Lions. Has a tinge of darkness beneath his chivalrous demeanor.
- Dedue Molinaro - A man from Duscur who was spared from his people's genocide by Dimitri. Owes him a life debt and is his most faithful servant.
- Annette Fantine Dominic - The intelligent yet absent minded estranged daughter of Gilbert and heir of House Dominic. Bearer of a Minor Crest of Dominic, she is the inheritor of the magical axe Crusher.
- Ashe Ubert - A former thief adopted by Lord Lonato. Aspires to be a knight like his adoptive older brother.
- Mercedes von Martritz - The adopted daughter of a merchant family with a gentle, easygoing personality. Bearer of a minor Crest of Lamine.
- Sylvain Jose Gautier - The skirt chasing heir of house Gautier and bearer of a Minor Crest of the same name, he is the inheritor of the Lance of Ruin.
- Felix Hugo Fraldarius - The sharp-tongued heir of house Fraldarius who challenges any person he deems strong to a duel. Bearer of a Major Crest of Fraldarius, he is the inheritor of the Aegis Shield.
- Ingrid Brandl Galatea - The knightly and chivalrous member of house Galatea and holder of a Minor Crest of Daphnel, she is the inheritor of the lance Lúin.
- Lambert Egitte Blaiddyd - The former heir of the Kingdom's throne who later became King of Faerghus. He is also Dimitri's father.
- Rodrigue Achille Fraldarius - The former heir of House Fraldarius and inseparable friend of Lambert, he later became Duke of Fraldarius and right hand of the King, known as "Shield of Faerghus". He also is Felix's father.
- Cassandra Rubens Charon - The headstrong and reckless member of House Charon known as"Thunderstrike Cassandra".
- Christophe Gaspard - The son of Lord Lonato and heir of House Gaspard, he was the adoptive elder brother of Ashe, and great friend with Cassandra of House Charon whom he went in the Academy with.
The Japanese pronunciation of the three classes take their names from German. The Blue Lions are roughly called "Löwenklasse," which means "Lion Class."
- The Blue Lions is the only house that has an unequal distribution of male and female members.
- The Blue Lions path (Azure Moon) is the route where the most playable characters can survive.
- It is also the only path where the player can obtain all 12 of the original Heroes' Relics, as Areadbhar and Crusher are unobtainable in the other routes, as one is Dimitri's signature Relic, while Gilbert, the second character needed for Annette's Paralogue, is a playable character found exclusively in the Azure Moon route.
- In a survey conducted by Nintendo DREAM Magazine, the Blue Lions ranked 1st among the houses chosen in Fire Emblem: Three Houses. The male-female vote ratio was 1:2. It received 42.6% of the vote.
- In the second survey conducted by Nintendo DREAM Magazine, the Blue Lions ranked 1st among the houses chosen in Fire Emblem: Three Houses. The male-female vote ratio was 1:3. It received 47.9% of the vote.
- In the fourth survey conducted by Nintendo DREAM Magazine, the Blue Lions ranked 1st among the houses chosen in Fire Emblem: Three Houses. The male-female vote ratio was 1:4. It received 50% of the vote.
- In the fifth survey conducted by Nintendo DREAM Magazine, the Blue Lions ranked 1st among the houses chosen in Fire Emblem: Three Houses. The male-female vote ratio was 1:4. It received 47% of the vote.