Henri Alphonse Barnoin was a French painter born in Paris in 1882.

Barnoin's father was an artist as were two of his uncles, and he studied art at the École des Beaux Arts in Paris. Although Barnoin initially studied with Luc-Olivier Merson, it was his second teacher, Émile Dameron, who became a more significant influence on his artistic style, attracting Barnoin to Impressionism. His work was part of the painting event in the art competition at the 1928 Summer Olympics.

He first exhibited his paintings at the Salon des Artistes de Paris in 1909. He continued to exhibit regularly at this annual Salon, winning a silver medal in 1921 and a gold medal in 1935. He chose to live in Concarneau in 1919, having been a frequent visitor to the port before the 1914–1918 war. There he opened a studio on the "Quai Pénéroff" which became a favourite meeting place for fellow artists all inspired by the light and animated scenes of fishing boats, village markets, and the sea. In 1926, Barnoin became official Artist to the French Navy. In addition to his oil paintings, he was a renowned pastellist, enjoying playing with the effect of light on a variety of scenes in a Post-Impressionist style. He died in Paris in 1940. Among Barnoin's favored subjects were marine, harbour, and coastal scenes, mostly painted in the rich settings of Brittany.