Ignacy Domeyko or Domejko (Lithuanian: Ignotas Domeika; Spanish: Ignacio Domeyko; Belarusian: Ігнат Дамейка) (July 31, 1802 – January 23, 1889, Santiago de Chile) was a 19th-century Polish geologist, mineralogist and educator. Domeyko spent most of his life (and died) in his adopted country, Chile.
After a youth passed in the partitioned Polish-Lithuanian lands, Domeyko participated in the November 1830 Uprising against the Russian Empire. Upon its suppression, he was forced into exile and spent part of his life in France before eventually settling in Chile, of which he became a citizen. He lived some 50 years in Chile and made major contributions to the study of that country's geography, geology and mineralogy. His observations on the circumstances of poverty-stricken miners and of their wealthy exploiters had a profound influence on those who would go on to shape Chile's labor movement.
Domeyko is seen as having had close ties to several countries and thus in 2002, when UNESCO organized a series of commemorations of the 200th anniversary of his birth, he was referred to as "a citizen of the world".