Isabelle Wilhelmine Marie Eberhardt (17 February 1877 – 21 October 1904) was a Swiss explorer and author. As a teenager, Eberhardt, educated in Switzerland by her father, published short stories under a male pseudonym. She became interested in North Africa, and was considered a proficient writer on the subject despite learning about the region only through correspondence. After an invitation from photographer Louis David, Eberhardt moved to Algeria in May 1897. She dressed as a man and converted to Islam, eventually adopting the name Si Mahmoud Saadi. Eberhardt's unorthodox behaviour made her an outcast among European settlers in Algeria and the French administration.

Eberhardt's acceptance by the Qadiriyya, an Islamic order, convinced the French administration that she was a spy or an agitator. She survived an assassination attempt shortly thereafter. In 1901, the French administration ordered her to leave Algeria, but she was allowed to return the following year after marrying her partner, the Algerian soldier Slimane Ehnni. Following her return, Eberhardt wrote for a newspaper published by Victor Barrucand and worked for General Hubert Lyautey. In 1904, at the age of 27, she was killed by a flash flood in Aïn Séfra.

In 1906, Barrucand began publishing her remaining manuscripts, which received critical acclaim. She was seen posthumously as an advocate of decolonisation, and streets were named after her in Béchar and Algiers. Eberhardt's life has been the subject of several works, including the 1991 film Isabelle Eberhardt and the 2012 opera Song from the Uproar: The Lives and Deaths of Isabelle Eberhardt.

Early life and family background Eberhardt was born in Geneva, Switzerland, to Alexandre Trophimowsky and Nathalie Moerder (née Eberhardt). Trophimowsky was an Armenian anarchist, tutor, and former Orthodox priest-turned-atheist who had been born a serf. Nathalie was the illegitimate daughter of a middle-class Lutheran German and a Russian Jew. Nathalie was considered to be part of the Russian aristocracy, meaning her illegitimacy was probably kept secret. She married widower Pavel deMoerder, a Russian general forty years her senior, who hired Trophimowsky to tutor their children Nicolas, Nathalie, and Vladimir.

Around 1871 Nathalie took the children and left her husband for Trophimowsky, who had abandoned his own wife and family. They left Russia, staying in Turkey and then Italy before settling in Geneva. Around 1872 Nathalie gave birth to Augustin; deMoerder, who came to Switzerland in a failed attempt to reconcile with Nathalie, accepted the son as his own and allowed him to have his surname, but the boy's older siblings believed that Trophimowsky was the father. General deMoerder died several months later, and despite their separation had arranged for his estate to pay Nathalie a considerable regular income. The family remained in Switzerland. Four years later Eberhardt was born, and was registered as Nathalie's illegitimate daughter. Biographer Françoise d'Eaubonne speculated that Eberhardt's biological father was the poet Arthur Rimbaud, who had been in Switzerland at the time. Other historians consider this unlikely and find it more likely that Trophimowsky was the father, noting that Nathalie and Trophimowsky were rarely apart, that Eberhardt's birth did not impact negatively on their partnership, and that Eberhardt was Trophimowsky's favourite child. Biographer Cecily Mackworth speculated that Eberhardt's illegitimacy was due to Trophimowsky's nihilist beliefs, which rejected traditional concepts of family.

Eberhardt was well educated; along with the other children in the family, she was home-schooled by Trophimowsky. She was fluent in French, spoke Russian, German and Italian, and was taught Latin, Greek, and classical Arabic. She may have learned the latter from her father, who was enthusiastic about Islam as an anti-colonial force. She studied philosophy, metaphysics, chemistry, history, and geography, though she was most passionate about literature, reading the works of authors including Pierre Loti, Jean-Jacques Rousseau, Leo Tolstoy, Voltaire and Émile Zola while she was a teenager, and was also an admirer of the poets Semyon Nadson and Charles Baudelaire. At an early age she began wearing male clothing, enjoying its freedom, and her nonconformist father did not discourage her. The children of deMoerder resented their stepfather, who forbade them from obtaining professions or leaving the home, and effectively used them as slaves to tend to his extensive gardens. Eberhardt's sister Nathalie married against Trophimowsky's wishes in 1888, and was subsequently cut off from the rest of the household. Nathalie's departure had a profound effect on Eberhardt's childhood, as she had been responsible for most of the home duties; the household subsequently suffered from a lack of hygiene and regular meals.

Move to North Africa Sometime prior to 1894, Eberhardt began corresponding with Eugène Letord, a French officer stationed in the Sahara who had placed a newspaper advertisement for a pen pal. Eberhardt asked him for every detail he could give her about life in the Sahara, also informing him of her dreams of escaping Geneva alongside her favourite sibling, Augustin. Letord encouraged the two of them to relocate to Bône, Algeria, where he could assist them in establishing a new life. In a series of circumstances that remain unclear though involving financial debts and ties to Russian revolutionist groups with which he was affiliated, Augustin fled Geneva in 1894. Eberhardt probably assisted him initially but was unable to keep track of his whereabouts despite making constant inquiries. In November 1894 Eberhardt was informed by a letter that Augustin had joined the French Foreign Legion and was assigned to Algeria. Though she was at first furious with Augustin's decision, Eberhardt's anger did not last; she asked him to send her a detailed diary of what he saw in North Africa.

In 1895, Eberhardt published short stories in the journal La Nouvelle Revue Moderne under the pseudonym of Nicolas Podolinsky; "Infernalia" (her first published work) is about a medical student's physical attraction to a dead woman. Later that year she published (), a story about North African religious life. Eberhardt had "remarkable insight and knowledge" of North Africa for someone acquainted with the region only through correspondence, and her writing had a strong anti-colonial theme. Louis David, an Algerian-French photographer touring Switzerland who was intrigued by her work, met with her. After hearing of her desire to move to Algiers, he offered to help her establish herself in Bône if she relocated there. In 1895, he took a photograph of Eberhardt wearing a sailor's uniform, which would become widely associated with her in later years. Around 1896, Eberhardt started a correspondence with the Egyptian actor Yaqub Sanu, who went on to become a close friend and introduced her to various Tunisian connections.

Eberhardt relocated to Bône with her mother in May 1897. They initially lived with David and his wife, who both disapproved of the amount of time Eberhardt and her mother spent with Arabs. Eberhardt and her mother did not like the Davids' attitude, which was typical of European settlers in the area, and later avoided the country's French residents, renting an Arabic-style house far from the European quarter. Eberhardt, aware that a Muslim woman could go out neither alone nor unveiled, dressed as a man in a burnous and turban. She expanded on her previous studies of Arabic, and became fluent within a few months. She and her mother converted to Islam. Mackworth writes that while Eberhardt was a "natural mystic", her conversion appeared to be largely for practical reasons, as it gave her greater acceptance among the Arabs. Eberhardt found it easy to accept Islam; Trophimowsky had brought her up as a fatalist and Islam gave her fatalism a meaning. She embraced the Islamic concept that everything is predestined and the will of God.

Although Eberhardt largely devoted herself to the Muslim way of life, she frequently consumed both marijuana and alcohol and had many lovers, including several of her Algerian acquaintances. According to a friend, Eberhardt "drank more than a Legionnaire, smoked more kief than a hashish addict and made love for the love of making love". She was heterosexual, but often treated sexual intercourse as impersonal. The reason for her Arabic companions' tolerance of her lifestyle has been debated by biographers. According to Mackworth, the "delicate courtesy of the Arabs" led them to treat Eberhardt as a man because she wished to live as one. Mark Sedgwick further states that Eberhard was serious about studying and committing to Sufi practice, even though she did not observe many aspects of the Sharia. Eberhardt's behaviour made her an outcast with the French settlers and the colonial administration, who watched her closely. Seeing no reason why a woman would choose the company of impoverished Arabs over her fellow Europeans, they eventually concluded she must be an English agent, sent to stir up resentment towards the French.

Eberhardt began to write stories, including the first draft of her novel Trimardeur (). Her story Yasmina, about a young Bedouin woman who falls in love with a French officer and the "tragedy this impossible love brings into her life", was published in a local French newspaper. Her mother, who had been suffering from heart problems, died in November 1897 of a heart attack, and was buried under the name of Fatma Mannoubia. Eberhardt was grief-stricken. Trophimowsky, who had been summoned when his partner's health had deteriorated but arrived after her death, showed no sympathy towards Eberhardt. When she told him she desperately wanted to die and rejoin her mother, he responded by calmly offering her his revolver, which she declined.

Travels to Europe Eberhardt spent her money recklessly in Algiers, and quickly exhausted the funds left to her by her mother; she would often spend several days at a time in kief dens. Augustin, ejected from the Foreign Legion due to his health, returned to Geneva alongside Eberhardt in early 1899. They found Trophimowsky in poor health, suffering from throat cancer and traumatised by the loss of Eberhardt's mother and Vladimir, who had committed suicide the previous year. Eberhardt nursed her father, growing closer to him. She also commenced a relationship and became engaged to Riza Bey, an Armenian diplomat with whom she had been friends and possibly lovers when she was seventeen. Though Trophimowsky approved of the engagement, the relationship soon ended. Historian Lesley Blanch attributes the relationship's downfall to Bey being assigned to Stockholm. Trophimowsky died in May. Blanch attributes the death to a chloral overdose, with which Eberhardt may have intentionally euthanised him. Eberhardt intended to sell the villa, although Trophimowsky's legitimate wife opposed the execution of the will. After several weeks of legal contentions, Eberhardt mortgaged the property and returned to Africa on the first available ship. With both parents dead, she considered herself free of human attachments and able to live as a vagabond. Eberhardt relinquished her mother's name, and called herself Si Mahmoud Saadi. She began wearing male clothing exclusively and developed a masculine personality, speaking and writing as a man. Eberhardt behaved like an Arab man, challenging gender and racial norms. Asked why she dressed as an Arab man, she invariably replied: "It is impossible for me to do otherwise." A few months later, Eberhardt's money ran low, and she returned to Geneva to sell the villa; due to the legal troubles there was little to no money available.