Eugene was born October 16, 1888 to Irish immigrant James O'Neill  and Mary Ellen Quinlan (also known as Ella O'Neill).
As a child, Eugene attended boarding school at St. Aloysius Academy for Boys.  He later attended Princeton University for a short time, leaving due to unconfirmed circumstances.
"Accounts vary as to why he left. He may have been dropped for attending too few classes,been suspended for "conduct code violations,"or "for breaking a window",or according to a more concrete but possibly apocryphal account, because he threw "a beer bottle into the window of Professor Woodrow Wilson", the future president of the United States."
Eugene became an American playwright and Nobel Prize laureate for his work in literature. Some of his best known plays are:
Eugene passed away on November 27, 1953, at a Sheraton Hotel in Boston.
His last words are said to have been: "I knew it. I knew it. Born in a hotel room and died in a hotel room." That hotel later became a dormitory at Boston University, with an urban legend that his spirit haunts the building. 
"United States Census, 1900," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:M97X-6VS : accessed 31 May 2019), Eugene G Oneil in household of James ? Oneil, New London city Ward 5, New London, Connecticut, United States; citing enumeration district (ED) 467, sheet 18B, family 405, NARA microfilm publication T623 (Washington, D.C.: National Archives and Records Administration, 1972.); FHL microfilm 1,240,149.