Reginald Bathurst Birch was an English-American artist and illustrator. He was best known for his depiction of the titular hero of Frances Hodgson Burnett's 1886 novel Little Lord Fauntleroy, which started a craze in juvenile fashion. While his illustrated corpus has eclipsed his other work, he was also an accomplished painter of portraits and landscapes.

Birch was born May 2, 1856 in London, England, the son of British army officer William Alexander Birch and Isabella (Hoggins) Birch. During his childhood he lived for a time with his paternal grandfather on the Isle of Jersey while his father was in India.

He moved to San Francisco, California with his parents in 1870. Afterward he was naturalized as a citizen of the United States.

Birch married twice and had two children, a son and a daughter. The son, Rodney Bathurst Birch, was an early film actor.

Birch died at the age of eighty-seven of congestive heart failure at the Home for Incurables in the Bronx, New York. His body was interred at Woodlawn Cemetery in New York.

Birch's artistic talent first emerged in San Francisco, where he helped his father prepare wood-block theatrical posters. He soon attracted a patron in painter Toby Edward Rosenthal, who allowed him to use his studio and helped further his artistic education. From 1873 to 1881 Birch studied and worked in Europe, attending the Royal Academy of Fine Arts in Munich and illustrating various publications in Vienna, Paris, and Rome.

On his return to the United States, Birch took up residence in New York City, where he became a magazine illustrator. His work appeared in St. Nicholas, the Century, Harper's, Life, and The Youth's Companion, among other publications. He also became a founding member of the Society of Illustrators in New York.

His first great success was his illustration of Frances Hodgson Burnett's children's book Little Lord Fauntleroy (1886), whose young protagonist's long, curly hair and velvet and lace suit were widely imitated by mothers as a pattern of dress for their little boys. Birch's name was indelibly associated with Burnett's protagonist forever after, rather to the illustrator's irritation. During the period of his initial popularity he illustrated over forty books, many of which, along with his drawings, had initially seen publication in serial form. These included more of Burnett's children's books, notably Sara Crewe (1888).

Demand for Birch's work faded after 1914, and by the 1930s he was living in poverty. His career was revived in 1933 by his illustrations for Louis Untermeyer's The Last Pirate, and he went on to illustrate about twenty additional books before being retired by failing eyesight about 1941. Reginald Birch—His Book, a retrospective collection of works he illustrated by various authors, was published in 1939 by Harcourt, Brace and Company.