Jacques Ellul (/ɛˈluːl/; French: [ɛlyl]; 6 January 1912 – 19 May 1994) was a French born philosopher, sociologist, lay theologian, resistance fighter and professor. Noted as a Christian anarchist, Ellul was a longtime professor of History and the Sociology of Institutions on the Faculty of Law and Economic Sciences at the University of Bordeaux. A prolific writer, he authored more than 60 books and more than 600 articles over his lifetime, many of which discussed propaganda, the impact of technology on society, and the interaction between religion and politics.

The dominant theme of Ellul's work proved to be the threat to human freedom and religion created by modern technology. He did not seek to eliminate modern technology or technique but sought to change our perception of modern technology and technique to that of a tool rather than regulator of the status quo. Among his most influential books are The Technological Society and Propaganda: The Formation of Men's Attitudes.

Considered by many a philosopher, Ellul was trained as a sociologist, and approached the question of technology and human action from a dialectical viewpoint. His writings are frequently concerned with the emergence of a technological tyranny over humanity. As a philosopher and theologian, he further explored the religiosity of the technological society. In 2000, the International Jacques Ellul Society was founded by a group of former Ellul students. The society, which includes scholars from a variety of disciplines, is devoted to continuing Ellul's legacy and discussing the contemporary relevance and implications of his work.

Jacques Ellul was born in Bordeaux, France, on 6 January 1912, to Marthe Mendes (Protestant; French-Portuguese) and Joseph Ellul (initially an Eastern Orthodox Christian, but then a Voltairian deist by conviction; born in Malta of an Italo-Maltese father and Serb mother). As a teenager he wanted to be a naval officer but his father made him study law. He married Yvette Lensvelt in 1937.

Ellul was educated at the universities of Bordeaux and Paris. In World War II, he was a leader in the French resistance. (For his efforts to save Jews he was awarded the title Righteous among the Nations by Yad Vashem in 2001.) He was a layman in the Reformed Church of France and attained a high position within it as part of the National Council.

Ellul was best friends with Bernard Charbonneau, who was also a writer from the Aquitaine region and a protagonist of the French personalism movement. They met through the Protestant Student Federation during the academic school year of 1929–1930. Both men acknowledged the great influence each had on the other.

By the early 1930s, Ellul's three primary sources of inspiration were Karl Marx, Søren Kierkegaard, and Karl Barth. Ellul was first introduced to the ideas of Karl Marx during an economics lecture course taught by Joseph Benzacar in 1929–30; Ellul studied Marx and became a prolific exegete of his theories. During this same period, he also came across the Christian existentialism of Kierkegaard. According to Ellul, Marx and Kierkegaard were his two greatest influences, and the only two authors whose work he read in its entirety. Also, he considered Karl Barth, who was a leader of the resistance against the German state church in World War II, the greatest theologian of the 20th century. In addition to these intellectual influences, Ellul also said that his father played a great role in his life and considered him his role model.

In large measure, and especially in those of his books concerned with theological matters, Ellul restates the viewpoints held by Barth, whose polar dialectic of the Word of God, in which the Gospel both judges and renews the world, shaped Ellul's theological perspective. In Jacques Ellul: A Systemic Exposition Darrell J. Fasching claimed Ellul believed "That which desacralizes a given reality, itself in turn becomes the new sacred reality".