Santiago Peñailillo was one of the main artists of the publishing house Zig Zag, best known for his contributions to the horror comic 'Dr. Mortis'. Born in Cauquenes, Pañailillo studied briefly at the Faculty of Fine Arts of Santiago in 1969. After working for newspaper for while, he joined Editorial Zig Zag in mid-1969. In August of that year, he did his first 'Dr Mortis' story, and continued working on the series for many years.
When Zig Zag became Quimantú in 1972, Peñailillo went to work for the magazines Infinito ('Eos Errante') and Dimensión Cero ('Aventura Espacial', 'Extraña Aventura'), while he also worked on new 'Dr. Mortis' stories with Juan Marino. In addition, he made 'Martin y Diana', with his own scripts, and 'Kouma, La Reina Blanca', with José Zamorano, in Mampato. He also did the puzzle comic 'Blackwel', and an adaptation of the medieval tale 'Amadís de Gaula'. For publisher Gabriela Mistral, he contributed to the magazines Intocable, Far West, Jungla and El Manque from 1974.
Since 1975, Peñailillo had also worked for La Tercera on supplements like Icarito, for which he did covers and a series about the history of Chile. He continued to draw for other supplements throughout the 1980's, and made historical comics through the Artecrom agency. He cooperated with artists like Mario Igor, Manuel Cárdenas, Julio Berrios and Themo Lobos. He eventually returned to La Tercera in 1983, and remained there until 2002, working on supplements like Icarito, De Mujer a Mujer, Agro, and En Su Casa. In the 1990's, he was present in Pimpín with new adventures of 'Martín y Diana'. In 2004, he launched his own horror magazine, Makabro.