Alférez (from Arabic الفارس al-fāris, meaning "horseman" or "cavalier") is a junior officer rank also used in Spain, Argentina and Chile. The variant Alferes was formerly used in both Portugal and Brazil. A naval variant, Frigate Alférez, is used in Spain and Peru.

Alférez is often translated as ensign. Although it does not derive from any meaning of carrying the flag, alférez was nonetheless the Spanish officer rank associated with the carrying of a unit flag. Alférez is also sometimes translated as sub-lieutenant or second lieutenant. These translations are approximate.

The rank of alférez was first used by Spanish armies during the reconquista in the middle ages. During that time alférez was the chief general of the king. The famous warrior El Cid was the alférez of Alfonso VI king of Castile

Argentina

In Argentina, the rank of alférez is used by both the air force and the gendarmerie. It is, however, used differently in the two services. The air force uses the rank for newly qualified officers, while the gendarmerie uses "alférez" ranks as an equivalent for the army's "lieutenant" ranks.

The other armed forces of Argentina do not use the rank of ensign.

Argentine Air Force Rank	Argentine Gendarmerie Rank	Equivalent Commonwealth Ranks for comparison
-------------	-------------	-------------
Alférez	Sub-Alférez	Acting Pilot Officer / 2nd Lieutenant
Lieutenant	Alférez	Pilot Officer / 2nd Lieutenant
First Lieutenant	First Alférez	Flying Officer / Lieutenant

Chile

In Chile, an officer cadet is known as a sub-alférez. On graduating from officer training, he becomes an alférez for a year while carrying out training specific to his arm. After this the alférez is promoted to sub-lieutenant.

Peru

Frigate Alférez is the lowest naval officer rank.

Spain

Alférez is the lowest officer rank in Spain, immediately below lieutenant. Frigate Alférez is the lowest naval officer rank.