Alexandru Vaida-Voevod or Vaida-Voievod (27 February 1872 – 19 March 1950) was an Austro-Hungarian-born Romanian politician who was a supporter and promoter of the union of Transylvania (before 1920 part of Hungary) with the Romanian Old Kingdom; he later served 28th Prime Minister of Romania.

He was born to a Greek-Catholic family in the Transylvanian village of Bobâlna (then Alparét, Austria-Hungary). Initially, Voevod was supportive of a plan to federalize the domains of the Habsburgs along the lines of a United States of Greater Austria, and was close to Archduke Franz Ferdinand.

In 1906, he joined a group of Romanian nationalists in the Budapest Parliament (the Romanian National Party of Transylvania and Banat), becoming an important opponent of the Hungarian governmental policy of Magyarization, and fought for the right of Transylvania to self-determination. Disappointed by the Austrian cause after Franz Ferdinand's assassination in Sarajevo, and turned towards an advocacy of Transylvania's union with Romania; he and his party presented a demand for self-determination along Wilsonian principles to the Hungarian legislative in October 1918.

In December 1918, after Hungary surrendered in World War I, he was part of the Transylvanian council that proclaimed the union with Romania, and was, alongside Vasile Goldiș, Iuliu Hossu, and Miron Cristea, a member of the Transylvanian group of envoys that presented the decision to KingFerdinand I in Bucharest.