Upton Beall Sinclair Jr. (September 20, 1878 – November 25, 1968) was an American author, muckraker journalist, and political activist, and the 1934 Democratic Party nominee for governor of California. He wrote nearly 100 books and other works in several genres. Sinclair's work was well known and popular in the first half of the 20th century, and he won the 1943 Pulitzer Prize for Fiction.
In 1906, Sinclair acquired particular fame for his muckraking fictional novel, The Jungle, which exposed the labor and sanitary conditions in the U.S. meatpacking industry, causing a public uproar that contributed in part to the passage a few months later of the 1906 Pure Food and Drug Act and the Meat Inspection Act. In 1919, he published The Brass Check, a muckraking exposé of American journalism that publicized the issue of yellow journalism and the limitations of the "free press" in the United States. Four years after publication of The Brass Check, the first code of ethics for journalists was created. Time magazine called him "a man with every gift except humor and silence" based on his wife Mary Craig Sinclair's book Southern Belle: A Personal Story of a Crusader's Wife.