Nikolay Stepanovich Leontiev, Count of Abai, (Russian: Никола́й Степа́нович Леонтьев; 26 October 1862 – 1910) was a Russian military officer and adviser, geographer and traveler, explorer of Africa, writer, first Count of the Ethiopian Empire, and veteran of the First Italo-Ethiopian War, the Boxer Rebellion, and the Russo-Japanese War.
Leontiev was born on 25 February 1862 to a noble family in Kherson Province. He studied in Nikolaev's Cavalry military school, then served in the Uhlan Leib Guard regiment. In 1891, he became esaul of a military reserve force of the Umansk regiment of the Kuban Cossack army.
Like Mashkov and Ashinov before him, Leontiev had dreamed of going to Ethiopia and for many years he collected information about the country. Finally, Leontiev was able to go to Ethiopia on a research trip. Famous scientists, the Science Academy and the Russian Geographical Society took great interest in this programme. But the main task of the Leontiev expedition was to establish friendly relations between Russia and Ethiopia.
Leontiev was the chief of the eleven-man Russian expedition;stabskapitan Zviagin was his deputy. The meeting between Leontiev and the Ethiopian emperor Menelik II set up the foundation for their mutual friendship. When Leontiev decided to go home, Menelik sent his first diplomatic mission to Russia with him, and in doing so abrogated an agreement with Italy that forbade such diplomatic missions.
Menelik invited Leontiev to return to Ethiopia with a Russian military mission. In 1895 Leontiev organized a delivery of Russian weapons for Ethiopia: 30,000 rifles, 5,000,000 cartridges, 5000 sabres, and a few cannons. The presence of the Russian advisers at the battle of Adwa helped the Ethiopians achieve victory in the first Italo-Ethiopian War. The Russian advisor Leonid Artamonov wrote that the Ethiopian artillery comprised 42 Russian mountain guns supported by a team of fifteen advisers.