The south Andean deer, also known as the southern guemal, south Andean huemul, southern huemul, or Chilean huemul or güemul, is an endangered species of deer native to the mountains of Argentina and Chile. Along with the northern guemal or taruca, it is one of the two mid-sized deer in the Hippocamelus genus and ranges across the high mountainsides and cold valleys of the Andes. The distribution and habitat, behaviour, and diet of the deer have all been the subject of study. The viability of the small remaining population is an outstanding concern to researchers.

A deer or true deer is a hoofed ruminant ungulate of the family Cervidae. It is divided into subfamilies Cervinae and Capreolinae. Male deer of almost all species, as well as female reindeer, grow and shed new antlers each year. These antlers are bony extensions of the skull and are often used for combat between males.