Christmas wafer is a Catholic Christmas tradition celebrated in Poland, Lithuania, Moravia, and Slovakia. The custom is traditionally observed during Kūčios in Lithuania and Wigilia in Poland on December 24.

Wigilia is the traditional Christmas Eve vigil supper in Poland, held on December 24. The term is often applied to the whole of Christmas Eve, extending further to Pasterka—midnight Mass, held in Roman Catholic churches all over Poland and in Polish communities worldwide at or before midnight. The custom is sometimes referred to as "wieczerza" or "wieczerza wigilijna", in Old Polish meaning evening repast, linked to the late church service, Vespers from the Latin.