The penultimate king of the dynasty of Avis, who disappeared in the Battle of Alcácer-Quibir, in 1578, is seen posing here at the age of 16, clad for the first time in a ceremonial suit of armour, and accompanied by a dog, a feature that brings this work close to the iconography established by the portrait of Carlos V, painted in 1530 by Jakob Seisenegger (Kunsthistoriches Museum, Vienna).

Dom Sebastião (1554-1578) had been raised in the court of Lisbon by his grandmother, Queen Catarina, the sister of Carlos V, since his mother, Joanna of Austria, had entered into retreat at the Convent of las Descalzas Reales, in Madrid. Paintings produced by Cristóvão de Morais were regularly sent by Queen Catarina to complete the series of portraits of the Habsburg family that Joanna had begun to collect at the convent. The taste for genealogical picture galleries of this nature spread throughout Europe, and it is known that Queen Catarina also established a portrait gallery of the House of Austria at the Paço da Ribeira.