Sasha was the creator of Tanya, Kate, and Irina: Tanya was initially a distant relative of Sasha. She was so intrigued by the idea of having another female vampire for company that she decided to turn Tanya; Within a century of Tanya's transformation, they came across Kate while attacking a carriage, and Sasha decided to create a sister to Tanya due to their physical resemblance and Kate's sense of loyalty; and later, Sasha came across Irina, a peasant girl living in a small farm community. She was so intrigued by her resemblance to Tanya and Kate that she turned her and adopted her into their family.
Tanya, Kate, and Irina all thought of her as a mother and she thought of them as her daughters. Sometime after their transformations, Sasha committed the ultimate crime by creating an immortal child: Vasilii. Due to the danger of the immortal children revealing the existence of vampires, the Volturi slaughtered them and anyone who knew of their existence, even humans. She kept his existence secret from Tanya and her sisters, to protect them from the fate of being executed by the Volturi, which indicated that she suspected it would happen. Eventually, her prediction came true when her child's indiscretion caught the Volturi's attention, and she and Vasilii were executed. Tanya and her sisters witnessed their mother's death but were spared the same fate due to their ignorance of the child's existence.
Sasha's death prompted her "daughters" to substitute animal blood for human to avoid killing; also, instilled a healthy respect for the laws of the vampire world in them, which prompted Irina to tell the Volturi that Bella and Edward Cullen of the Olympic coven created an immortal child; she did not know that Bella and Edward conceived half-human and half-vampire hybrid when Bella was still human. This mistake resulted in Irina's death, again, at the hands of the Volturi.
After centuries of mourning, the sisters were still upset with Sasha's execution, though they never truly forgave her for committing the crime, and avoided mentioning her at all ways possible.
Sasha's appearance was never explored in the books. In the movie, however, she showed blonde hair and the traditional red vampire eyes. Her appearance was more mature than her daughters'.
- Sasha's name was never mentioned in Breaking Dawn. Her name remained shrouded due to Carlisle not knowing it when he talked to Bella about her.