Ruth "Rutka" Laskier (12 June 1929 – December 1943) was a Jewish Polish diarist who is best known for her 1943 diary chronicling three months of her life during the Holocaust in Poland.

Following the German invasion of Poland, while in the Będzin Ghetto, Rutka Laskier, age 14, wrote a 60-page diary in Polish, chronicling several months of her life under the Nazi rule in 1943.

[4] Laskier's family was forced to move to the newly formed Jewish Ghetto in Będzin during the Holocaust in World War II.

Rutka was deported from the ghetto and was believed to have been murdered in a gas chamber, age 14, along with her mother and brother, upon arrival with her family at the Auschwitz concentration camp in August 1943.

Zofia Minc (later Galler), a fellow prisoner who survived, revealed in a published account of her time at Auschwitz, that Laskier slept in the barrack next to her until falling victim to a cholera outbreak in December 1943.

[11] From 19 January to 24 April 1943, without her family's knowledge, Laskier kept a diary in an ordinary school notebook, writing in both ink and pencil, making entries sporadically.

In it, she discussed atrocities she witnessed committed by the Nazis, and described daily life in the ghetto, as well as innocent teenage love interests.

In 2005, Adam Szydłowski, the chairman of the Center of Jewish Culture of the Zagłębie Region of Poland, was told by one of Sapińska's nieces about the existence of the diary.

Coincidentally, Rutka Laskier was born the same day as Anne Frank,[3] and, in both cases, of their entire families, only their fathers survived the war.

In June 2007, Yad Vashem Publications published English and Hebrew translations of the diary, entitled Rutka's Notebook: January–April 1943.