James Montgomery Flagg (June 18, 1877 – May 27, 1960) was an American artist and illustrator. He worked in media ranging from fine art painting to cartooning, but is best remembered for his posters.
Flagg was born in Pelham Manor, New York. He was enthusiastic about drawing from a young age, and had illustrations accepted by national magazines by the age of twelve years. By fourteen he was a contributing artist for Life magazine, and the following year was on the staff of another magazine, Judge. From 1894 through 1898, he attended the Art Students League of New York. He studied fine art in London and Paris from 1898–1900, after which he returned to the United States, where he produced countless illustrations for books, magazine covers, political and humorous cartoons, advertising, and spot drawings. Among his creations was a comic strip that appeared regularly in Judge from 1903 until 1907, about a tramp character titled Nervy Nat.