Alexandru Nicolau (Russian: Александр Александрович Николау, romanized: Aleksandr Aleksandrovich Nikolau; January 1889 – September 27, 1937) was a Romanian lawyer, socialist and later communist activist.

As a student at the Saint Sava High School, he befriended Constantin Titel Petrescu and Mihail Cruceanu, both of whom would later become known as socialist militants.

[8] In order to escape harassment from the authorities, Nicolau chose to leave Romania for Paris, where he continued his law studies at the Sorbonne, and joined the French Section of the Workers' International.

[9][10][11] In 1916, Romania joined World War I on the side of the Entente and imposed an immediate ban on the local socialist movement, which had adopted a militant pacifist stance.

[12][10] Joining Rakovsky and Bujor, Nicolau left in June 1917 for Russia,[13] where he entered the Russian Social Democratic Labour Party (bolsheviks).

[14] He settled in Odessa and, along with Bujor, Ion Dic Dicescu, and Alter Zalic, he was one of the organisers and afterwards leaders of the Romanian Committee for Social-Democratic Action established in the city.

[21] The occupation of Odessa by Austro-German troops in the aftermath of the Treaty of Brest-Litovsk forced the volunteer battalions to retreat to Crimea and central Russia, with the members of the Action Committee either going underground or leaving for Russian areas still under Soviet control.

Alexandru Nicolau returned to Romania in 1920, however he was soon apprehended by the authorities, and imprisoned in Jilava along with a larger group of communists, including Alecu Constantinescu.

[26] Nicolau also joined the Romanian section of the Communist University of the National Minorities of the West, where he lectured on topics such as history and social sciences, and worked as a teacher for the Moscow Institute of Foreign Languages.

Along with Dicescu, the main author of the document, Nicolau considered Moldovans to be Romanians, and saw the new polity primarily as a base for propaganda across the Dniester, in Bessarabia and Romania.

[27] Arrested on August 14, 1937, during the Stalinist purges, Nicolau was sentenced to death on September 27, 1937, by the Military Collegium of the Supreme Court of the USSR on fabricated charges of "espionage and involvement in counter-revolutionary terrorist organisations".