Alexander Eig (1894, near Minsk, Belarus - 30 July 1938, Jerusalem, Israel) was a botanist, one of the first plant researchers in Israel, head of the department of Botany at the Hebrew University in Jerusalem and co-founder of the Jerusalem Botanical Gardens on Mount Scopus.
Born in Schedrin near Minsk, he used to wander in the forests and to join his family on hunting and fishing expeditions observing the plants around. At the age of 15 he immigrated to Palestine, where he became a student in "Mikveh Israel" agricultural school.
In 1925 he was invited by Otto Warburg to join the agricultural experimental station in Tel Aviv, where he worked with Michael Zohary. A year later, the unit moved to Jerusalem, and they joined the staff of the Hebrew University of Jerusalem. In that year he married Itta Faktorovsky, the sister of his closest friend and fellow botanist Elazar Faktorovsky.
On 1931 he graduated with his Ph.D., and founded the Jerusalem Botanical Gardens on Mount Scopus, together with Zohary and Naomi Feinbron. On 1932 he started teaching botany. Among his students were the brothers Aaron and Ephraim Katzir.
On 1937 he was invited by Yitzhak Ben-Zvi to testify before the Peel Commission, on the question of whether the country could sustain a large population. He was later asked to prepare a map that would serve the arguments of the Zionist side in the international arena.
Eig died of cancer in 1938, at the age of less than 44 years. He was buried in the cemetery on the Mount of Olives;his gravestone bears the inscription "The creator of plant science in Israel." He was eulogized by Moshe Sharett, Hugo Bergmann, Judah Leon Magnes and Yitzhak Ben-Zvi.