Eugene O'Neill is widely accepted to be the first American playwright to write tragedies. He had a troubled childhood, and this is reflected in the somber mood of his plays. His mother became a morphine addict directly after his birth, and he always blamed himself for this. From the very beginning, he felt guilty just for being born.
When he was in his early twenties, he attempted suicide. Throughout the course of his life, he married three times. His third wife was the actress Carlotta Monteray, whom he loved intensely. He actually had an affair with Carlotta Monteray during his second marriage.
Probably his most defining characteristic is that he wrote copious amounts of stage directions. Some of his critics argue that this was almost "cheating", because it resembled prose. He actually did these stage directions because he published his plays with the intent that they would be read as well as seen.
He died in 1953.