Main article: Lists of atheists
* John Anderson (1893–1962): Scottish-born Australian philosopher, founder of the empirical philosophy known as 'Sydney realism'.
* Hector Avalos (1958–): Mexican-American professor of Religious Studies at Iowa State University and author of several books about religion.
* A. J. Ayer (1910–1989): British philosopher and advocate of logical positivism. Though technically he viewed the idea of God existing as meaningless, he was happy to call himself an atheist.
* Julian Baggini (1968–): British writer specialising in philosophy, author of Atheism: A Very Short Introduction.
* Mikhail Bakunin (1814–1876): Russian philosopher, writer and anarchist.
* Jonathan Barnes (1942–): British philosopher, translator and historian of ancient philosophy, and brother of the novelist Julian Barnes.
* Bruno Bauer (1809–1882): German philosopher, theologian and historian, the first propounder of the Jesus myth hypothesis.
* Simone de Beauvoir (1908–1986): French author and existentialist philosopher. Beauvoir wrote novels and monographs on philosophy, politics, social issues and feminism.
* Simon Blackburn (1944–): British academic atheist philosopher known for his efforts to popularise philosophy.
* Yaron Brook (1961–): Israeli-born president and executive director of the Ayn Rand Institute.
* Ludwig Büchner (1824–1899): German philosopher, physiologist and physician who became one of the exponents of 19th century scientific materialism.
* Albert Camus (1913–1960): French philosopher and novelist, a luminary of existentialism. He won the Nobel Prize in Literature in 1957.
* Rudolf Carnap (1891–1970): German philosopher who was active in central Europe before 1935 and in the United States thereafter. He was a leading member of the Vienna Circle and a prominent advocate of logical positivism.
* Robert Todd Carroll (1945–): American writer and academic, professor of philosophy at Sacramento City College until 1997, and keeper of the Skeptic's Dictionary website.
* David Chalmers (1966-): Australian philosopher of mind.
* Noam Chomsky (1928–): American linguist, philosopher, political activist, author, and lecturer, Institute Professor and professor emeritus of linguistics at the Massachusetts Institute of Technology, credited with the creation of the theory of generative grammar.
* Auguste Comte (1798–1857): French positivist thinker, credited with coining the term "sociologie" (sociology).
* André Comte-Sponville (1952–): French philosopher, author of L'Esprit de l'athéisme (2006) and The Little Book of Atheist Spirituality (2007).
* Marquis de Condorcet (1743–1794): French philosopher, mathematician, and early political scientist who devised the concept of a Condorcet method.
* Benedetto Croce (1886–1952): Italian philosopher and public figure.
* Gilles Deleuze (1925–1995): French philosopher of the late 20th century. From the early 1960s until his death, Deleuze wrote many influential works on philosophy, literature, film, and fine art.
* Daniel Dennett (1942–): American philosopher, author of Breaking the Spell.
* Henry Louis Vivian Derozio (1809–1831): Anglo-Indian poet and teacher.
* Diagoras of Melos (5th century BCE): Ancient Greek poet and sophist known as the Atheist of Milos, who declared that there were no Gods.
* Denis Diderot (1713–84): editor-in-chief of the Encyclopédie.
* Theodore Drange (1934–): Philosopher of religion and Professor Emeritus at West Virginia University. Drange authored Nonbelief & Evil: Two arguments for the nonexistence of God.
* Paul Edwards (1923–2004): Austrian-American moral philosopher and editor of The Encyclopedia or Philosophy.
* Dylan Evans (1966–): British philosopher, known for his work on emotion and the placebo effect.
* Ludwig Andreas Feuerbach (1804–1872): German philosopher whose major work, The Essence of Christianity, maintains that religion and divinity are projections of human nature.
* Friedrich Karl Forberg (1770–1848): German philosopher and classical scholar.
* Michel Foucault (1926–1984) : French philosopher and social theorist famous for his influential analysis of power and discourse. He is best known for his revolutionary philosophical analyses of social institutions such as Discipline and Punish and The History of Sexuality.
* A. C. Grayling (1949–): British philosopher and author of, among others, Against All Gods: Six Polemics on Religion and an Essay on Kindness.
* John Harris (1947–): British professor of bioethics at the University of Manchester, and member of the UK Human Genetics Commission.
* Claude Adrien Helvétius (1715–71): French philosopher whose ethical and social views helped shape the school of utilitarianism later made famous by Jeremy Bentham.
* Baron d'Holbach (1723–1789): French philosopher and encyclopedist, most famous as being one of the first outspoken atheists in Europe.
* David Hume (1711–1776): Scottish philosopher, economist, historian and a key figure in the history of Western philosophy and the Scottish Enlightenment.
* Corliss Lamont (1902–1995): American humanist and Marxist philosopher, and advocate of various left-wing and civil liberties causes.
* David Kellogg Lewis (1941–2001): American philosopher. One of the leading thinkers of the second half of the 20th century.
* Peter Lipton (1954–2007): British philosopher, the Hans Rausing Professor and Head of the Department of History and Philosophy of Science at Cambridge University until his unexpected death in November 2007. He was "one of the leading philosophers of science and epistemologists in the world."
* Kazimierz Łyszczyński (1634–1689): Polish noble and philosopher, author of a philosophical treatise De non existentia Dei (On the Non-existence of God), condemned to death and executed for atheism.
* John Leslie Mackie (1917–1981): Australian philosopher who specialized in meta-ethics as a proponent of moral skepticism. Wrote The Miracle of Theism, discussing arguments for and against theism and concluding that theism is rationally untenable.
* Michael Martin (1932–): analytic philosopher and professor emeritus at Boston University, author of, amongst others, Atheism: A Philosophical Justification (1989) and The Impossibility of God (2003).
* Harriet Martineau (1802–1876): was an English writer and philosopher, renowned in her day as a controversial journalist, political economist, abolitionist and life-long feminist.
* Karl Marx (1818–1883): philosopher, political economist, sociologist, humanist, political theorist and revolutionary. Often called the father of communism, Marx was both a scholar and a political activist.
* Colin McGinn (1950–): British philosopher and author, best known for his work in the philosophy of mind.
* Jean Meslier (1678–1733): French village Catholic priest who was found, on his death, to have written a book-length philosophical essay, entitled Common Sense but commonly referred to as Meslier's Testament, promoting atheism.
* Julien Offray de La Mettrie (1709–51): French physician and philosopher, earliest materialist writer of the Enlightenment, claimed as a founder of cognitive science.
* John Stuart Mill (1806–1873): The famous philosopher declared his atheism, and that of his father, in a famous essay published posthumously.
* Michael Neumann (1946–): American professor of philosophy at Trent University, noted for his work on utilitarianism, rationality and antisemitism.
* Kai Nielsen (1926–): adjunct professor of philosophy at Concordia University in Montreal and professor emeritus of philosophy at the University of Calgary.
* Friedrich Nietzsche (1844–1900): German philosopher whose Beyond Good and Evil sought to refute traditional notions of morality. Nietzsche penned a memorable secular statement of the Doctrine of Eternal Recurrence in Thus Spake Zarathustra and is forever associated with the phrase, "God is dead" (first seen in his book, The Gay Science).
* Piergiorgio Odifreddi (1950–): Italian mathematician, philosopher and science writer.
* Michel Onfray (1958–): French philosopher, founder of Université populaire de Caen, and author of Atheist Manifesto: The Case Against Christianity, Judaism, and Islam.
* Graham Oppy (1960–): Australian philosopher and Associate Dean of Research at Monash University, and Associate Editor of the Australasian Journal of Philosophy. His main area of research is the philosophy of religion.
* Leonard Peikoff (1933–): an Objectivist philosopher, Ayn Rand's legal heir. He is a former professor of philosophy, a former radio talk show host, and founder of the Ayn Rand Institute.
* Herman Philipse (1951–): professor of philosophy at Utrecht University in the Netherlands. Philipse has written many philosophical works in Dutch, including the widely-read Atheist Manifesto and the Unreasonableness of Religion (Atheistisch manifest & De onredelijkheid van religie.
* Karl Popper (1902-1994): Austrian-British philosopher and professor at the London School of Economics
* James Rachels (1941–2003): American philosopher who specialized in ethics.
* Ayn Rand (1905–1982): Russian-American founder of Objectivism and novelist.
* Jean-François Revel (1924–2006): French politician, journalist, author, prolific philosopher and member of the Académie française.
* Michael Ruse (1940–): English philosopher of science, known for his work on the argument between creationism and evolutionary biology.
* Bertrand Russell, (1872–1970): British philosopher and mathematician. He won the Nobel Prize in Literature in 1950. Though he considered himself an agnostic in a purely philosophical context, he said that the label atheist conveyed a more accurate understanding of his views in a popular context.
* George Santayana (1863–1952): Philosopher in the naturalist and pragmatist traditions who called himself a "Catholic atheist."
* Jean-Paul Sartre (1905–1980): French existentialist philosopher, dramatist and novelist who declared that he had been an atheist from age twelve. Although he regarded God as a self-contradictory concept, he still thought of it as an ideal toward which people strive. He rejected the Nobel Prize for Literature in 1964. According to Sartre, his most-repeated summary of his existentialist philosophy, "Existence precedes essence," implies that humans must abandon traditional notions of having been designed by a divine creator.
* Michael Schmidt-Salomon (1967–): German philosopher, author and former editor of MIZ (Contemporary Materials and Information: Political magazine for atheists and the irreligious)
* Arthur Schopenhauer (1788–1860): Pessimistic German philosopher and author of the book The World as Will and Representation.
* John Searle (1932–): American philosopher, Slusser Professor of Philosophy at the University of California, Berkeley, widely noted for contributions to the philosophy of language, the philosophy of mind, and to social philosophy.
* Peter Singer (1946–): Australian utilitarian philosopher, proponent of animal rights, and Ira W. DeCamp Professor of Bioethics at Princeton University.
* George H. Smith (1949–): Libertarian philosopher, author and educator. Smith authored Atheism: The Case Against God.
* Quentin Smith (1952–): Philosopher and professor of philosophy at Western Michigan University. Smith co-authored the book Theism, Atheism and Big Bang Cosmology with William Lane Craig.
* Carlo Tamagnone (1937–): Italian philosopher. Theorician and historian of atheism. Wrote whether works of theoretical proposal or of historical analysis.
* Theodorus the Atheist (lived around 300 BCE): Philosopher of the Cyrenaic school who taught that the goal of life was to obtain joy and avoid grief.
* Sir Bernard Williams FBA (1929–2003): British philosopher, widely cited as the most important British moral philosopher of his time.
* Sherwin Wine (1928–2007): Founder of the non-theistic Society for Humanistic Judaism, who has also called himself an "ignostic".
* Slavoj Žižek (1949–): Slovenian sociologist, postmodern philosopher, and cultural critic.
* Bruce Lee: martial artist, actor and philosopher. He majored in philosophy at the University of Washington. John Little states that Lee was an atheist. When asked in 1972 what his religious affiliation was, he replied "none whatsoever." Also in 1972, when asked if he believed in God, he responded, "To be perfectly frank, I really do not."