Henri Julien Félix Rousseau was a French post-impressionist painter in the Naïve or Primitive manner. He was also known as Le Douanier (the customs officer), a humorous description of his occupation as a toll and tax collector. He started painting seriously in his early forties; by age 49, he retired from his job to work on his art full-time.

Ridiculed during his lifetime by critics, he came to be recognized as a self-taught genius whose works are of high artistic quality. Rousseau's work exerted an extensive influence on several generations of avant-garde artists.

Rousseau was born in Laval, Mayenne, France, in 1844 into the family of a tinsmith; he was forced to work there as a small boy. He attended Laval High School as a day student, and then as a boarder after his father became a debtor and his parents had to leave the town upon the seizure of their house. Though mediocre in some of his high school subjects, Rousseau won prizes for drawing and music.

After high school, he worked for a lawyer and studied law, but "attempted a small perjury and sought refuge in the army." He served four years, starting in 1863. With his father's death, Rousseau moved to Paris in 1868 to support his widowed mother as a government employee.

In 1868, he married Clémence Boitard, his landlord's 15-year-old daughter, with whom he had six children (only one survived). In 1871, he was appointed as a collector of the octroi of Paris, collecting taxes on goods entering Paris. His wife died in 1888 and he married Josephine Noury in 1898.

From 1886, he exhibited regularly in the Salon des Indépendants, and, although his work was not placed prominently, it drew an increasing following over the years. Tiger in a Tropical Storm (Surprised!) was exhibited in 1891, and Rousseau received his first serious review when the young artist Félix Vallotton wrote: "His tiger surprising its prey ought not to be missed; it's the alpha and omega of painting." Yet it was more than a decade before Rousseau returned to depicting his vision of jungles.

In 1893, Rousseau moved to a studio in Montparnasse where he lived and worked until his death in 1910. In 1897, he produced one of his most famous paintings, La Bohémienne endormie (The Sleeping Gypsy).

In 1905, Rousseau's large jungle scene The Hungry Lion Throws Itself on the Antelope was exhibited at the Salon des Indépendants near works by younger leading avant-garde artists such as Henri Matisse, in what is now seen as the first showing of The Fauves. Rousseau's painting may even have influenced the naming of the Fauves.

In 1907, he was commissioned by artist Robert Delaunay's mother, Berthe, Comtesse de Delaunay, to paint The Snake Charmer.

When Pablo Picasso happened upon a painting by Rousseau being sold on the street as a canvas to be painted over, the younger artist instantly recognised Rousseau's genius and went to meet him. In 1908, Picasso held a half serious, half burlesque banquet in his studio at Le Bateau-Lavoir in Rousseau's honour. Le Banquet Rousseau, "one of the most notable social events of the twentieth century," wrote American poet and literary critic John Malcolm Brinnin, "was neither an orgiastic occasion nor even an opulent one. Its subsequent fame grew from the fact that it was a colorful happening within a revolutionary art movement at a point of that movement's earliest success, and from the fact that it was attended by individuals whose separate influences radiated like spokes of creative light across the art world for generations."

Guests at the banquet Rousseau included: Guillaume Apollinaire, Jean Metzinger, Juan Gris, Max Jacob, Marie Laurencin, André Salmon, Maurice Raynal, Daniel-Henri Kahnweiler, Leo Stein, and Gertrude Stein.

After Rousseau's retirement in 1893, he supplemented his small pension with part-time jobs and work such as playing a violin in the streets. He also worked briefly at Le petit Journal, where he produced a number of its covers. Rousseau exhibited his final painting, The Dream, in March 1910, at the Salon des Independants.

In the same month Rousseau suffered a phlegmon in his leg, one which he ignored. In August, when he was admitted to the Necker Hospital in Paris where his son had died, he was found to have gangrene in his leg. After an operation, he died from a blood clot on 2 September 1910.