Corneliu Zelea Codreanu (September 13, 1899 – November 30, 1938)—born Corneliu Zelinski and commonly known as Corneliu Codreanu—is a Romanian politician of the far right, the founder and charismatic leader of the Iron Guard or The Legion of the Archangel Michael (also known as the Legionary Movement), an ultra-nationalist and violently anti-Jewish organization active throughout most of the interwar period.

Generally seen as the main variety of local fascism, and noted for its mystical and Romanian Orthodox-inspired revolutionary message, it grows into an important actor on the Romanian political stage, coming into conflict with the political establishment and the democratic forces, and often resorting to terrorism.

The Legionaries traditionally refer to Codreanu as Căpitanul ("The Captain"), and he holds absolute authority over the organization until his death.

Codreanu, who begins his career in the wake of the First World Wa as an anticommunist and anti-Jewish agitator associated with A. C. Cuza and Constantin Pancu, is a co-founder of the National-Christian Defense League and assassin of the Iaşi Police prefect Constantin Manciu.

Codreanu leaves Cuza to found a succession of movements on the far right, rallying around him a growing segment of the country's intelligentsia and peasant population, and inciting pogroms in various parts of Greater Romania.

Several times outlawed by successive Romanian cabinets, his Legion assumes different names and survives in the underground, during which time Codreanu formally delegates leadership to Gheorghe Cantacuzino-Grănicerul.

Following Codreanu's instructions, the Legion carries out assassinations of politicians it viewed as corrupt, including Premier Ion G. Duca and his former associate Mihai Stelescu.

Simultaneously, Corneliu Zelea Codreanu advocates Romania's adherence to a military and political alliance with Nazi Germany.

He registers his main electoral success during the 1937 suffrage, but is blocked out of power by King Carol II, who comes to favor rival fascist alternatives around the National Christian Party and the National Renaissance Front.

The rivalry between Codreanu and, on the other side, Carol and moderate politicians like Nicolae Iorga ends with the former's imprisonment at Jilava and eventual assassination at the hands of the Gendarmerie.

He is succeeded as leader by Horia Sima.

In 1940, under the National Legionary State proclaimed by the Iron Guard, his killing serves as the basis for violent retribution.

Corneliu Zelea Codreanu's views influence the modern far right.

Groups claiming him as a forerunner include Noua Dreaptă and other Romanian successors of the Iron Guard, the International Third Position, and various neofascist organizations in Italy and other parts of Europe.