6 February] 1878 – 12 June 1937) was a Russian Bolshevik revolutionary, politician, and the younger sister of Vladimir Lenin and Anna Ulyanova.

In 1895, Maria applied to the physicochemical department of the mathematical faculty of the Higher (Bestuzhev) women's courses in Saint Petersburg.

She conducted propaganda in workers' circles, delivered illegal literature, and acted as a liaison officer.

In September 1899, after the arrests of members of the Moscow RSDLP, Maria was sent under police supervision to Nizhny Novgorod.

The third time she was arrested was in January 1904, and then having been released on bail in June of the same year, Maria left for Switzerland.

In the summer of 1910, hiding from arrest, Maria worked as a home teacher in the village of Leppenino near the station Terijoki (Grand Duchy of Finland).