Alexander Ivanovich Voeikov (Александр Иванович Вое́йков; 1842 - 1916) was a Russian meterologist and climatologist who conducted groundbreaking research on climate, especially in his native Russia. He studied at St. Petersburg University before undertaking further studies in Germany, earning a doctorate in 1865 at the University of Göttingen. He traveled extensively throughout the world and helped to establish many meteorological stations. In 1887, he became a professor at his alma mater, St. Petersburg University. Late in his career, he was among the most eminent Russian climate scientists as well as a vocal proponent of vegetarianism.