Timothy H. O'Sullivan (1840 –1882) was a photographer widely known for his work related to the American Civil War and the Western United States. As a teen he worked with Matthew Brady. O'Sullivan took many of the iconic photographs we know today of the carnage of the Civil War. After the war he was official photographer on the United States Geological Exploration in the West and later joined the Panama Canal survey team. O'Sullivan died in Staten Island of tuberculosis at age 42.