Guillermo Marín began alternating the lyrical genre with the dramatic in the twenties, because his mother was an actress. One of his first interventions as a baritone was in the company of Salvador Videgain and Pepe Moncayo meeting at the opening of the Chueca theater in Madrid in 1926. Trained in the theater during the 20s in Ricardo Calvo theatre company, his stage career spanned 40 years. During these 40 years he formed his own company several times, got several hits and received twice the National Theatre Award in 1970 and 1982. Considered an institution in the Spanish theater, he remained onstage until his death, at 83 years and a few months after playing "Cassandra." He had many and memorable film appearances in the '40s, specially under director Edgar Neville's orders, specializing in distinguished roles. Guillermo Marín was very appreciated in the profession and managed to shoot in some international productions that got popularity at the time.