Mario Arnello Romo (born 25 December 1925) is a Chilean lawyer, scholar, poet and politician, and one of the founders of the right-wing National Party in 1966.

During Augusto Pinochet's dictatorship (1973–1990), Arnello was director of DIBAM (1986–1990) and special ambassador both at United Nations (1974–1978) and in the Organization of American States (1974–1976).

Around 1938–1941 seasons, he felt attraction for nationalist ideas, so that he had sympathy towards to National Socialist Movement of Chile, the fascist murdered group in the Seguro Obrero massacre (1938) under Alessandri Palma's second government (1932–1938).

In early 1940s, he joined Universidad de Chile School of Laws, receiving him with a thesis called "Syndicalism", which was approved with distinction.

A time later after his certification, he reached a scholarship from Instituto de Cultura Hispánica (then controlled by francoism) for a PhD in law at University of Madrid.