Hadji Oumarûl Foutiyou Tall (ʿUmar ibn Saʿīd al-Fūtī Ṭaʿl, Arabic: حاج عمر بن سعيد الفوتي طعل, c. 1794 – 1864 CE), born in Futa Tooro, present-day Senegal, was a Senegalese Tijani sufi Toucouleur Islamic scholar and military commander who founded the short-lived Tukulor Empire, which encompassed much of what is now Senegal, Mauritania, Guinea and Mali.

Omar Tall’s name is spelt variously: in particular, his first name is commonly transliterated in French as Omar, although some sources prefer Umar; the patronymic, ibn Saʿīd, is often omitted; and the final element of his name, Tall (Arabic: طعل), is spelt variously as Tall, Taal or Tal.

The honorific El Hadj (also al-Hajj or el-Hadj), reserved for a Muslim who has successfully made the Hajj to Mecca, precedes Omar Tall's name in many texts, especially those in Arabic. Later he also took on the honorifics Amir al-Mu'minin, Khalifa, Qutb (pole of the universe), vizier of the Mahdi, Khalifat Khatim al-Awliya (successor of the seal of saints), and Almami (Imam).

Omar Tall was born about 1794 in Halwar in the Imamate of Futa Toro (present-day Senegal), the tenth of twelve children. His father was Saidou Tall, from the Torodbe lineage, and his mother was Sokhna Adama Aissatou Thiam.

Omar Tall attended a madrassa before embarking on the Hajj in 1828, during which he learned from the scholars of Al Azhar University. While in Mecca he stayed with Muhammad al Ghali [fr], the head of the Tijaniyyah order, who made him a muqaddam (commander) of the order with a commission to destroy paganism in the Sudan. He returned in 1830 as a marabout with the title El Hadj and assumed the khalifa of the Tijaniyya Sufi order in the Sudan. El-Hadj took the Tijani honorific Khalifat Khatim al-Awliya. This authority would become the basis of the authority necessary to lead Africans.

When returning from the Hajj, he camped near Damascus, where he met Ibrahim Pasha, Omar Tall befriended the Pasha and healed his son from a deadly fever. The trends set by the Pasha highly inspired Omar Tall.^{[citation needed]}

Settling in Sokoto from 1831 to 1837, he entered into a polygynous marriage, with one of the women being the daughter of the Fula caliph of the Sokoto Caliphate, Muhammed Bello. In 1837, Omar Tall moved to the Imamate of Futa Jallon and founded his religious settlement at Jegunko in 1840. Omar Tall claimed a transcendental personal authority. He denied the importance of adherence to a madhhab and favoured ijtihad or personal religious judgment. He taught that a believer should follow the guidance of a Sufi shaykh who has immediate personal knowledge of the divine truth. Even though Omar Tall never took the title of either mujaddid or Mahdi, he was regarded as such by his followers. He became the Torodbe ideal of religious revival and conquest of pagans.

Omar Tall's message appealed to a large cross-section of the Sahelian population in the mid-19th century, including Fula, Soninke, Moors, and others. Many lower-class people had grievances against local religious or military elites. Slaves aspired to gain freedom fighting for Islam. Rootless individuals of mixed ethnic backgrounds found new social identities and opportunities. Communities under the power of Europeans looked to Tall to drive off the foreigners. Marabout families hoped to gain political power in addition to their religious influence.