| Gaston | |
| Prince of Viana | |
| House: | Foix |
| Father: | Gaston IV, Count of Foix |
| Mother: | Infanta Eleanor of Navarre (later Queen of Navarre) |
| Spouse: | Magdalena of Valois |
| Issue: | Francis Phoebus, King of Navarre Catherine, Queen of Navarre |
| Birth Date: | 1445 |
| Death Place: | Libourne |
Gaston, Prince of Viana, also called Gaston de Foix (1445 – 23 November 1470), was the son and heir of Gaston IV, Count of Foix, and Infanta Eleanor of Navarre (later Queen of Navarre). As the expected successor to his mother and his grandfather, John II of Navarre, he was called Prince of Viana.
Gaston married Magdalena of Valois, a daughter of Charles VII of France and Marie of Anjou on 7 March 1461 at Lescar. They had two children:
Gaston died in 1470 from wounds received in a jousting tournament in Libourne, Aquitaine, before his accession to the throne of Navarre. Consequently, his children rose to the throne successively, but it was Gaston's wife Magdalena who actually pulled the strings of the crown until 1494.