Who is the mother of Lexie Grey?

The mother of Lexie Grey is Susan Grey. Lexie, whose full name is Alexandra Caroline Grey, is the daughter of Susan and Thatcher Grey, and the older full sister of Molly Grey-Thompson.

Susan is also Meredith Grey’s stepmother. Thatcher was previously married to Ellis Grey, Meredith’s mother, so Lexie and Meredith are half-sisters rather than full sisters. Lexie did not initially know Meredith well, but the two gradually developed a close bond after Lexie joined Seattle Grace Hospital.

Susan dies after a rare complication connected to treatment for acid reflux and persistent hiccups. Her death profoundly affects Thatcher and contributes to his later struggle with alcoholism. Lexie leaves a residency opportunity at Massachusetts General Hospital and returns to Seattle to help care for her grieving father.

A common mix-up is choosing Ellis Grey, because Ellis is Meredith’s mother and Lexie’s former stepmother. Maggie Pierce is also related to Meredith, but she is Ellis’s daughter with Richard Webber—not Lexie’s mother.