Alférez or alferes is a junior officer rank in the militaries of some Hispanophone and Lusophone countries.

The name originates from al-fāris (Arabic: الفارس), meaning "the knight", "the horseman" or "the cavalryman".^{[citation needed]} However, today the rank is often translated as ensign, sub-lieutenant or second lieutenant.^{[citation needed]}

The rank was first used by Iberian armies during the reconquista in the Middle Ages, being associated to the officer responsible for the carrying of a unit flag. During that time alférez was the leader of the retinue of a king or high-ranking nobleman. The famous warrior El Cid was the alférez of King Alfonso VI of Castile and Alfonso Núñez was the alférez of Duke Raymond of Galicia.^{[citation needed]}

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.

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 branch. After this, the alférez is promoted to sub-lieutenant.

The rank of alférez, locally spelled as alpéres, was also used by the Philippine Revolutionary Army during the Philippine Revolution and Philippine–American War. It is the lowest commissioned officer rank and is interchangeable with second lieutenant (Spanish: segundo teniente; Tagalog: ikalawang tenyente) on the service.

Alférez is the lowest officer rank in Spain, immediately below lieutenant. It's also the entry level for Voluntary Reservists.^[1]

	OF-1
Spanish Army[2]
		Alférez
Spanish Navy[2]
	Alférez de navío	Alférez de fragata
Spanish Air and Space Force[2]
		Alférez

• 
  Alférez
  (Chilean Army)^[3]
• 
  Alférez
  (Army of Equatorial Guinea)
• 
  Alferes
  (Mozambican Army)
• 
  Alferes
  (Portuguese Army)^[4]
• 
  Alferes
  (Army of São Tomé and Príncipe)
• 
  Alférez
  (Spanish Army)^[2]
• 
  Alférez
  (National Army of Uruguay)^[5]