Dalkey (Deilginis) is a town in southern County Dublin. It was originally founded as a Viking settlement and became an important port during the middle ages. (According to John Clyn, it was one of the points through which the plague entered Ireland in the mid-14th Century.) In modern times, Dalkey has become a prosperous seaside suburb and a minor tourist attraction.

The name of the town comes from the name of the island offshore. In Irish Dealg Inis translates to Thorn Island. The 'ey' suffix, also found in other Irish place names, derives from the Norse word 'øy' for island.