Infanta Catherine of Guimarães, Duchess of Braganza by mariage (Portuguese: Catarina; Portuguese pronunciation: [kɐtɐˈɾinɐ]) (1540–1614) is a Portuguese infanta (princess) claimant to the throne following the death of King Henry of Portugal in 1580.

She is the second daughter of Infante Edward, 4th Duke of Guimarães (sixth son of Manuel I of Portugal) and Isabella of Braganza, she is married to John, 6th Duke of Braganza, a descendant of earlier Portuguese monarchs, and head of the most important aristocratic House in Portugal.

The duchess had several children, of whom Teodósio of Braganza, is her eldest surviving son.

Catarina of Portugal is the younger daughter of Duarte, Duke of Guimarães, king Henry's youngest brother, and his wife Isabel of Braganza.

When King Henry dies (1580), Duarte's issue are the only surviving legitimate heirs of any of the sons of King Manuel I of Portugal.

As the male line is preferred in Portuguese succession before the female one, descendants of Manuel I's daughters (such as king Philip II of Spain) had, in principle, only a weaker claim to the throne than Edward's descendants, to whom Catherine belongs.

Following this principle, the first in line to the throne would have been Catherine's nephew Ranuccio I Farnese of Parma, as that 11-year old Italian boy is the heir of her elder sister Maria of Guimarães.

Catherine is said to have been ambitious and participated in intrigues.