Lieserl Einstein (Serbian Cyrillic: Лизерл Ајнштајн) (February 4, 1902 – ?) was the first child of physicist Albert Einstein and Mileva Marić.
According to letters exchanged by Albert and Mileva, Lieserl was born in Novi Sad, Serbia, and was cared for by her mother in Serbia while Albert worked in Switzerland.
Lieserl developed scarlet fever in early 1903.
Michele Zackheim, in her book on Lieserl, Einstein's Daughter, states that Lieserl was mentally challenged at birth, and that she probably died of scarlet fever as an infant.
Another possibility, favored by Robert Schulmann of the Einstein Papers Project, is that Lieserl was adopted by Maric's close friend, Helene Savic (Serbian Cyrillic: Хелене Савић), and was raised by her and lived under the name "Zorka Savic" (Serbian Cyrillic: Зорка Савић) until the 1990s. Savic did in fact raise a child by the name of Zorka, who was blind from childhood and died in the 1990s.
Lieserl's existence was unknown to biographers until 1986, when a batch of letters between Albert and Mileva was discovered by their granddaughter. The last known mention of Lieserl was on September 19th, 1903 in a letter from Mileva to Albert; the wording is possibly telling him about her death. Lieserl was never again mentioned in their extant correspondence.
"Lieserl" is also a character in the science fiction novel Ring by Stephen Baxter.