Infante Philip Prospero was a Prince of Asturias — a principality in medieval Spain. He was born in 1657 to King Philip IV of Spain and Maria Anna, an Austrian archduchess originally betrothed to the king's eldest son from a previous marriage. Philip was one of five children produced by the union but died at just 3 years old. His siblings included Margarita Teresa, Maria Ambrosia, Thomas Karl, and Charles.

Philip, Maria Ambrosia, and Thomas Karl all died in childhood. Philip had been perpetually ill since birth and died in 1661. Maria Ambrosia likely suffered from epilepsy and survived about 15 days while Thomas Karl died at 4 months old. Margarita Teresa survived childhood and married her uncle Leopold I, however, she died at the age of 21 from complications after her sixth pregnancy.

Charles, Philip's youngest brother, would eventually take the throne, reigning from 1665 until 1700. However, his severe medical and cognitive issues left him at the mercy of those around him, and he was never more than a pawn in a power struggle between various factions including his mother, his illegitimate half-brother, and his wife.