大角鹿（学名Megaloceros giganteus），又名巨大角鹿、巨型鹿或爱尔兰麋鹿，是体型最大的鹿。牠生存于更新世晚期及全新世早期的欧亚大陆，由爱尔兰至贝加尔湖东。最近年代的化石约为属于7700年前。大角鹿的大量化石现正在爱尔兰都柏林的爱尔兰自然历史博物馆展览。

传统上大角鹿被称为爱尔兰麋鹿。虽然有大量的骨骼在爱尔兰发现，但牠们却不只限于爱尔兰，加上牠其实与麋鹿不是近亲，故现时很多学者都只称呼牠为大角鹿。现今的物种都可能是从M. antecedens在近埃姆间冰期演化而来。M. antecedens有时被认为是一个亚种，称为M. giganteus antecedens，牠的鹿角相似但更为复杂。

The Irish elk (Megaloceros giganteus) or Irish giant deer, is an extinct species of deer in the genus Megaloceros and is one of the largest deer that ever lived. Its range extended across Eurasia, from Ireland to northern Asia and Africa. A related form is recorded from China during the Late Pleistocene. The most recent remains of the species have been carbon dated to about 7,700 years ago in Siberia. Although most skeletons have been found in bogs in Ireland, the animal was not exclusive to Ireland and was not closely related to either of the living species currently called elk - Alces alces (the European elk, known in North America as the moose) or Cervus canadensis (the North American elk or wapiti). For this reason, the name "Giant deer" is used in some publications, instead of "Irish elk". A study has suggested that the Irish elk was closely related to the Red deer (Cervus elaphus). However, other phylogenetic analyses support the idea of a sister-group relationship between fallow deer (Dama dama) and the Irish elk.