Ecaterina Arbore, Arbore-Ralli or Ralli-Arbore (rendered into Russian as Екатерина Арборе or Арборэ - Yekaterina Arborye or Arbore, with "Ralli" as Ралли; 1873 or 1875–1937), daughter of Zamfir Arbore (a socialist militant in Imperial Russia), was a Romanian, Soviet and Moldovan communist activist and official.
She trained towards a medical degree, and became committed to socialism and the Social Democratic Party during her University years. As such, Ecaterina Arbore took part in the proceedings of the 2nd Congress of the Second International in 1903, and she served as member of the Executive Committee of the Socialist Party.
She campaigned for an efficient preventive medicine, especially as an answer to the rising incidence of tuberculosis within large groups of the industrial worker population (as stated in her 1907 medical sociology work, Influenţa industriilor asupra sănătăţii lucrătorilor). At the same time, she demanded increased social security, and tried herself to improve conditions, mainly by creating the very first crèches in Romania.
After the October Revolution, she became an enthusiastic supporter of the Bolshevik cause, opting to leave Romania for Bolshevist Russia in 1918. Once there, after being received in the ranks of the CPSU, Ecaterina Arbore was integrated in the administrative structure of the Ukrainian SSR, as Commissar for Health.