He was the son of Portuguese King Peter I and a Galician noblewoman named Inês de Castro who had arrived in Portugal as a maid of princess Constance of Castile, recently married to Pedro I (Heir Prince at the time). Some historians consider him a natural son of Peter I, so the title Infante of Portugal could never be attributed to him.
Considering Denis an Infante of Portugal is a debatable subject. Lady of Cifuentes, born c. 1360, illegitimate daughter of Henry II of Castile by Juana, 1st? Fernando de Portugal, 3rd? Pedro de Portugal, 1st Lord of Colmenarejo (born c 1385), married to Isabel Enríquez (born c 1390), and had issue now extinct in male line
Beatriz de Portugal (died aft 1467), unmarried and without issue
He died in 1397.
