Mother Bertranda, O.P. (née Janina Siestrzewitowska; 1900–1988), later known as Anna Borkowska, was a Polish cloistered Dominican nun who served as the prioress of her monastery in Kolonia Wileńska near Wilno (now Pavilnys near Vilnius, Lithuania). She was a graduate of the University of Kraków who had entered the monastery after her studies. During World War II, under her leadership, the nuns of the monastery sheltered 17 young Jewish activists from Vilnius Ghetto and helped the Jewish Partisan Organization (FPO) by smuggling weapons. In recognition of this, in 1984 she was awarded the title of Righteous among the Nations by Yad Vashem.