Antônio Conselheiro, in English "Anthony the Counselor", real name Antônio Vicente Mendes Maciel (13 March 1830 – 22 September 1897), was a Brazilian religious leader, preacher and founder of the village of Canudos, the scene of the War of Canudos (1896–1897), a civil rebellion against the central government which was brutally stamped out with the loss of more than 25,000 lives.

Born in Quixeramobim, Antônio Maciel was the son of Maria Joaquina de Jesus and Vicente Mendes Maciel, who headed a moderately successful business in the sertão ("backlands"), the semi-arid zone of the Brazilian Northeast. His infancy was marked by a bloody feud with the powerful family of the Araújos, causing many deaths in both families, following the tragic cycle of vengeance and honour which were so common in these regions. After the death of his mother in 1834, his father married again, and Antônio and his two sisters suffered with the father's alcoholism and maltreatment by their stepmother. Antônio went to study with his grandfather, Manoel Antônio Ferreira Nobre, who was a teacher in Quixeramobim. He developed well as a serious, quiet and hard-working pupil, studying Latin, French, Portuguese, mathematics, geography and history. In 1855 his father died and he assumed the family's business, striving to get his sisters married. In 1857, Antônio himself married Brasilina Laurentina de Lima and began working as a salesman, teacher and lay counselor (poorman's lawyer). Already with two children, he was cheated on by his wife in 1861, and disillusioned and depressed, he separated from them and retired to a farm, working as a rural teacher, and devoting himself more and more to Christian mysticism. Moving again to Santa Quitéria, Ceará, he had a third child, a son named Joaquim Aprígio, after a brief affair with a local artist named Joana Imaginária. He was restless, however, and started to wander around the country, from 1865 to 1869, and then from 1871 and afterwards.

He was tall and thin, with long black hair and beard, always dressed in a rough blue tunic, a straw hat and leather sandals, carrying a necklace with a wooden cross, Antônio Maciel cut an impressive figure, reminding people of Jesus Christ. Gradually he became a pilgrim, an itinerant benefactor and counsellor of the poor, as well a pious preacher and religious leader. He was called alternatively by the simple people of the region as Antônio Conselheiro, Santo Antônio dos Mares, Santo Antônio Aparecido or Bom Jesus Conselheiro, and began to attract not only admirers, but fanatical followers, who started travelling with him.

In 1874, Antônio Conselheiro began to attract the attention of authorities and the Catholic Church, due to his preaching to the oppressed and poor peasants and common folk of small villages and farms. In 1876 he was arrested by the police in Itapicuru, Bahia, under the suspicion of being a wanted criminal. After being identified, he was sent by ship to Fortaleza. He was severely beaten, his hair and beard were cut and he was sent back for trial to his city of origin, Quixeramobim. The local judge, however, released Antônio Conselheiro due to the absence of any criminal charges against him. Antônio returned immediately to Bahia and restarted his wandering and preaching. He vowed to construct 21 churches and proceeded to do so in 12 cities in the backlands of the provinces of Bahia and Sergipe, as well as cemeteries and small dams.

In 1877, one of the periodical catastrophic droughts began in the Northeast. It would last two years killing more than 300,000 peasants by hunger and thirst, creating havoc with the predominantly semi-arid agrarian economy of the region. Many villages were entirely abandoned and instances of cannibalism even occurred. Antônio Conselheiro and his followers did what they could to diminish the extreme suffering of the poor people, adding more and more admirers and followers to his group. The sense of an impending end of the world and that the only salvation could come through religion were strong incentives to the surge of religious fanaticism. Conselheiro was widely regarded as a saint and a Messiah. Due to his increasing criticism of the official Church, and his open preachings in the small churches of the backlands, in 1882 the Archbishop of Bahia issued an order forbidding priests to allow him access to the flocks and characterising Antônio Conselheiro as an apostate and as a madman.

In 1888 and 1889, Brazil went through the most revolutionary and far-reaching social, economic and political changes of its history since Europeans settled in 1500. On 13 May 1888, slavery was abolished by the ruling Emperor, Dom Pedro II, by an act signed by his daughter, Princess Isabel. More than five million black people were suddenly free, and they abandoned the farms and swelled enormously the rural and urban ranks of extremely poor inhabitants. Tens of thousands of farmers went bankrupt and agriculture almost stopped for a while, particularly for cash crops which required intensive labor, such as coffee, cotton, tobacco and sugarcane, the mainstays of the Brazilian economy at the time. On 15 November 1889, the Emperor was deposed by a military coup and the Republic was proclaimed, further adding instability and strife to the already torn-up country.

All this was important to the make-up of Canudos. Antônio Conselheiro was strongly against slavery, and had preached and written about it, incurring the wrath of farmers and authorities. The number of his flocks increased dramatically, and it is estimated that over 80% were former slaves. In addition, he considered that monarchy was a grant of God, and that the Republic, with its separation between Church and State, was morally wrong and would wreck the country and family, a kind of new antichrist. Again he stepped up public criticism and rallied the social movement around these flags. General nervousness of farmers, priests and government increased to hysterical fear.

Finally, in 1893, violence erupted. Protesting against taxes levied by the new Republican government in Masseté, state of Bahia, "Conselhistas" (as Antônio Conselheiro's organized following was named) were attacked by a small police force and retaliated.