Was the first filmmaker to be recognized as a Philippine National artist
His father, Hermogenes IIagan, was a stage director and writer, his mother Casiana de Leon, was a singer
In 1937, De Leon played a part in MGA PUSONG DAKILA
In 1938, he directed his first film, the musical Bahay Kubo
Anong Ganda Mo, was his film that was interrupted by WW2 but eventually released in 1942
During Japanese occupation, De Leon, directed stage plays and after the war, he directed three films for Sampaguita Pictures - SO LONG AMERICA (1946), ISUMPA MO, GILIW (1947), and MAMENG, INIIBIG KITA (1947)
In his films, he departed from the conventions of the Tagalog movie and made use of expressionist images
Produced many films, "Daigdig ng mga Api, Noli Me Tangere, El Filibusterismo, Sisa, Sawa sa Lumang Simbolo, and Dyesebel