| Isabel | |
| Lady of Reguengos de Monsaraz, Colares and Belas | |
| House: | Braganza |
| Father: | Afonso I, Duke of Braganza |
| Mother: | Beatriz Pereira de Alvim |
| Spouse: | John, Constable of Portugal |
| Birth Date: | October 1402 |
| Birth Place: | Barcelos |
| Death Place: | Arévalo |
| Burial Place: | Batalha Monastery |
Isabel of Barcelos (October 1402 – 26 October 1466), also known as Isabel of Braganza, was a lady of the Portuguese nobility during the Late Middle Ages. She was the daughter of Afonso I, Duke of Braganza and Beatriz Pereira de Alvim, and she married Infante John, Lord of Reguengos de Monsaraz, her half-uncle, son of John I of Portugal.
Isabel and Infante John had four children:
Isabel died in the town of Arévalo on 26 October 1466 at the age of sixty-four. She was buried in the Batalha Monastery alongside her husband.