A Holocaust memorial day or Holocaust remembrance day is an annual observance to commemorate the victims of the Holocaust, the genocide of six million Jews and of millions of other Holocaust victims by Nazi Germany and its allies. Many countries, primarily in Europe, have designated national dates of commemoration. In 2005, the United Nations instituted an international observance, International Holocaust Remembrance Day.

Many observances fall on 27 January, the anniversary of the liberation of Auschwitz concentration camp in 1945, while other countries selected separate dates, often to mark anniversaries of national events during the Holocaust. Holocaust remembrance days often include efforts to combat hatred and antisemitism.

In February 2025, Google announced that Holocaust Remembrance Days would no longer be highlighted by default on Google Calendar, arguing that it was no longer "scalable or sustainable" to continue adding the growing number of national and international "cultural moments" manually to its calendars.

As of 2004^[update], twelve countries observed January 27, the day of the liberation of the Auschwitz concentration camp, including Germany, Britain, Italy and Scandinavian countries. In 2003 France designated this date as the day of remembrance of genocides and prevention of crimes against humanity. In 2004 Israel designated this date as a mark of the struggle against antisemitism.

As of 2004^[update], eleven countries in Europe had chosen dates related to local histories.