Villiers de l'Isle-Adam was born in Saint-Brieuc, Brittany, to a distinguished aristocratic family. His parents, Marquis Joseph-Toussaint and Marie-Francoise (née Le Nepvou de Carfort) were not rich, however, and were financially supported by Marie's aunt, Mademoiselle de Kerinou. His father became obsessed with the idea he could restore the family fortune by finding the lost treasure of the Knights of Malta (Philippe Villiers de L'Isle-Adam, 16th century Grand Master of the Knights Hospitaller, was his ancestor), which had reputedly been buried near Quintin during the French Revolution. Consequently, he spent large sums of money buying land, excavating it and then selling it at a loss when he failed to find anything of value. The young Villiers' education was troubled (he attended over half a dozen different schools) but from an early age his family were convinced he was an artistic genius: as a child he composed poetry and music. The most important occurrence in these Breton years was probably the death of a young girl with whom Villiers was in love, an event which would deeply influence his literary imagination.
Villiers had made several trips to Paris in the late 1850s, where he became enthralled by artistic and theatrical life. In 1860, his aunt gave him enough money to allow him to live in the capital permanently. He had already acquired a reputation in literary circles for his inspired, alcohol-fuelled monologues. Villiers began living a Bohemian life, frequenting the Brasserie des Martyrs, where he met his idol Baudelaire, who encouraged him to read the works of Edgar Allan Poe. Poe and Baudelaire would become the biggest influences on Villiers' mature style, but his first publication (at his own expense), was a book of verse, Premieres Poésies (1859). It made little impression outside Villiers' own small band of admirers. Around this time, Villiers began living with Louise Dyonnet, a woman whose reputation scandalised his family so much they made Villiers undergo a retreat at Solesmes Abbey. Villiers would remain a devout, if highly unorthodox, Catholic for the rest of his life.
Villiers finally broke with Dyonnet in 1864. His attempts at securing a suitable bride for himself would all end in failure. In 1867, he asked Théophile Gautier for the hand of his daughter Estelle, but Gautier - who had turned his back on the Bohemian world of his youth and would not let his child marry a writer with few prospects - turned him down. Villiers' own family also strongly disapproved of the match. His plans for marriage to an English heiress, Anna Eyre Powell, were equally unsuccessful. Villiers finally took to living with Marie Dantine, the illiterate widow of a Belgian coachman. In 1881, she gave birth to Villiers' son, Victor (nicknamed "Totor").
A high point of Villiers' life was his trip to see his hero Richard Wagner at Triebschen in 1869. Villiers read from the manuscript of his play La Révolte and the composer declared that the Frenchman was a "true poet". Another trip to see Wagner the next year was cut short by the outbreak of the Franco-Prussian War, during which Villiers became a commander in the Garde Nationale. At first he was impressed by the patriotic spirit of the Commune and wrote articles in support of it in the Tribun du peuple under the pseudonym "Marius", but he soon became disgusted with its revolutionary violence.
Disaster came in 1871 with the death of Villiers' aunt, Mlle de Kerinou, and the end of her financial support. Though Villiers had many admirers in literary circles (the most important being his close friend Stéphane Mallarmé), mainstream newspapers found his fiction too eccentric to be saleable and few theatres risked putting on his plays. Villiers was forced to take odd jobs to support his family: he gave boxing lessons and apparently worked in a funeral parlour and as a mountebank's assistant for a time. Another money-making scheme Villiers considered was reciting his poetry to a paying public in a cage full of tigers, but he later thought better of the idea. According to his friend Léon Bloy, Villiers was so poor he had to write most of his novel L'Eve future lying on his belly on bare floorboards because the bailiffs had taken away all the furniture. His poverty only increased his sense of aristocratic pride. In 1875, he attempted to sue a playwright he believed had insulted one of his ancestors, Maréchal Jean de Villiers de l'Isle Adam. In 1881, Villiers stood unsuccessfully for parliament as a candidate for the legitimist party. By the 1880s, there was some change in fortune: Villiers' fame began to grow, but not his finances. The publishers Calmann-Lévy accepted his Contes cruels, but the sum they offered Villiers was negligible. The volume did, however, come to the attention of J.-K. Huysmans, who praised Villiers' work in his highly influential novel A rebours. But by this time, Villiers was dying of stomach cancer. On his deathbed, he finally married Marie Dantine, thus legitimising his beloved son "Totor".
Villiers' works, in the romantic style, are often fantastic in plot and filled with mystery and horror. Important among them are the drama Axel (1890), the novel L'Ève future ("Tomorrow's Eve") (1886), and the short-story collection, Contes cruels (1883, tr. Sardonic Tales, 1927). L'Ève future greatly helped to popularize the term "Android" (Andréide in French).
Villiers believed the imagination has within it much more beauty than reality itself, existing at a level which nothing real could compare.
Axël was the work Villiers considered his masterpiece, although critical opinion has often been reluctant to agree with him, placing far higher value on his fiction. Villiers began work on the piece around 1869 and had still not put the finishing touches to it when he died. It was first published posthumously in 1890. The play is heavily influenced by the Romantic theatre of Victor Hugo, as well as Goethe's Faust and the music dramas of Richard Wagner. The scene is set in Germany in 1828 and opens on Christmas Eve in the convent of Saint Apollodora, where the rich heiress Sara de Maupers is just about to take the veil. But when the archdeacon asks Sara whether she is ready to accept "light, hope and life", she replies "no". The religious authorities attempt to imprison Sara, but she manages to flee. The rest of the drama takes place in the castle of Axël d'Auersperg, a young nobleman distantly related to Sara. Axël's cousin Kaspar has learnt that a vast treasure is buried near the castle. He tries to persuade Axël to help him look for it but Axël refuses, the two quarrel and Axël kills Kaspar in a duel. In the third act, Axël's Rosicrucian tutor, Master Janus, prepares to initiate Axël into the occult mysteries. He asks his pupil whether he is ready to accept "light, hope and life", and Axël replies "no". In Act Four, Axël decides to leave the castle forever and goes down to the crypt to say farewell to the tombs of his ancestors. Here he surprises Sara, who has been led to the castle by an old manuscript which tells of the location of the buried treasure. A door opens and the treasure pours out. Axël and Sara fight then fall in love. They dream of the glorious future the treasure will bring them then declare their dreams are far too magnificent to be fulfilled in everyday, unimaginative reality. They decide to kill themselves and die as the sun rises. The play's most famous line is Axël's "Vivre? les serviteurs feront cela pour nous" ("Living? Our servants will do that for us"). Edmund Wilson used the title Axel's Castle for his study of early Modernist literature.