Eugene O'Neill was born in New York City on October 16, 1888 to James and Ella O'Neill. James was a successful touring actor and O'Neill's mother, Ella, accompanied her husband touring around the country. Eugene was born in a hotel room and spent most of his childhood on the road with his family. Summers were spent in the family's only permanent home in New London, Connecticut. O'Neill was educated at boarding schools in his early years and then attended Princeton University for a year, from 1906 to 1907. After Eugene left school he began an education in, what he later called, "life experience." Over the next six years he shipped to sea, lived destitute on the waterfronts of New York, Buenos Aires and Liverpool, became alcoholic and attempted suicide. At age twenty-four, O'Neill finally began to recover from this state and held a job as a reporter for the New London Daily Telegraph. Eugene was forced to quit his reporting job when he became extremely ill with tuberculosis and was subsequently hospitalized in Gaylord Farm Sanitarium in Wallington, Connecticut for six months. While in the hospital, Eugene began to reevaluate his life in what he later termed his "rebirth." After his hospitalization, O'Neill studied the techniques of playwriting at Harvard University from 1914 to 1915 under the famous theater scholar George Pierce Baker.

In the summer of 1916, O'Neill made his first appearance as a playwright in a tiny playhouse on the wharf of Provincetown, MA. The playhouse was started as a new experimental theater by a group of young writers and painters. The playhouse produced Bound East for Cardiff, O'Neill's first play. This same group of writers formed the Playwrights' Theater in New York's Greenwich Village, eventually Provincetown Players, where O'Neill made his New York debut. For ten years O'Neill worked as a dramatist and playwright for this company. O'Neill's first full-length endeavor was produced on Broadway on February 2, 1920 at the Morosco Theater. Beyond the Horizon won the Pulitzer Prize for drama, the first of four awarded to O'Neill in his lifetime. O'Neill was later awarded Pulitzers for Anna Christie, Strange Interlude, and Long Day's Journey into Night. O'Neill was also the first American playwright to receive the Nobel Prize for literature.

Between 1920 and 1943, O'Neill completed twenty long plays and many shorter ones. All of O'Neill's plays are written from a personal point of view and reflect on the tragedy of the human condition. There is no doubt that O'Neill's early history contributed to his writing. Like O'Neill as a boy, many of his characters are caught in destructive situations and paths that they cannot escape. Before O'Neill, most American Drama was farce or melodrama. O'Neill embraced the theater as a venue to work out serious social issues and ideas. He transformed the American Theater into a serious and important cultural institution.

O'Neill has been compared to virtually every literary figure in the Western world and is considered the first great American playwright. His plays deal specifically with the American tragedy, rooted in American history and social movements. O'Neill had broad vision and was sometimes criticized when this vision seemed to exceed his skill. Some critics even believed O'Neill aimed too consciously at greatness. His dramas are marked by expressionistic theatrical techniques and symbolic devices that function to express religious and philosophical ideas. O'Neill even used the Ancient Greek Chorus as a device to comment on the action of many of his plays. By bringing psychological depth, poetic symbolism and expressionistic technique to the American theatre, O'Neill raised the standards of American theatre.

The last twenty years of his life, O'Neill battled a crippling nervous disorder similar to Parkinson's disease. He died in 1953.