Louis Loeb was a Jewish illustrator in the United States. In his time, he was one of the best known in his field. He was also a draftsman, a painter, and a lithographer.

Born in Cuyahoga County, Ohio to Alexander Loeb, a dry goods merchant, Louis Loeb worked at a Cleveland lithography firm from age 14 onwards, later taking evening classes in sketching at the Cleveland Art Club. In 1885, he worked at a lithography firm in New York City, with his evenings spent at the Art Students League.

In 1889 he went to Paris to study, under Lefebvre, Constant, and Gérôme, giving up lithography. After three years he returned to New York, where in 1893 he started work for The Century Magazine as an illustrator. For the next few years, up until 1900, he was to travel to and from Europe, both for study and in the course of his work for The Century. During the remainder of his life, he stayed in the U.S., dying in Canterbury, New Hampshire.