After his artistic studies at the Escuela Panamericana del Arte, Horacio Nestor Lalia made his professional debut in Hora Cero in 1964 and began a collaboration with the publishing house Columba in the following year. He assisted among others Eugenio Zoppi and Alberto Breccia on their work, and made appearances in El Tony and D'Artagnan. From 1966 to 1968 he worked for the British market, making several war stories for the Fleetway agency through the Solano Lopez studios. Between the late 1970s and late 1980s, he was present at the British market again with stories for 2000 AD. He also worked for publishers in Italy (Eura), Spain (Norma), Germany (Bastei) and France (Albin Michel).
At the same time he worked for the Argentinian daily La Razón and the Spanish publishing house Bruguera. From 1975 he became one of the main illustrators of the publishing house Record. After several short stories, he commenced working on 'Nekrodamus', the final large comics project by scriptwriter Hector German Oesterheld. Lalia drew this character until 1994 in Argentina and until 1998 in Italy (Eura).
In later years, he has focused on adaptations of suspense and horror literature.
He has made several albums with comics versions of the work of H. P. Lovecraft (Albin Michel), and he has also done comics based on the work of Edgar Allan Poe and H.G. Wells ('La Guerra de los Mundos', 2006).