The American writer known for his novel "The Great Gatsby" is F. Scott Fitzgerald. Published in 1925, the novel portrays the decadence and excess of the Jazz Age, focusing on themes of ambition, love, and the American Dream. Through the character of Jay Gatsby, Fitzgerald explores the disillusionment that often accompanies the pursuit of wealth and status. His work has become a classic, reflecting an era while questioning the moral underpinnings of society.