The Orsimer (more commonly known as Orcs), are the native people of the Wrothgarian and Dragontail Mountains. Despite historical misconceptions, they are in fact a variant of elves or mer, hence the name Orsimer, meaning "Pariah Ones". Following in the footsteps of Trinimac, and subsequently Malacath, Orcs have consistently held a standard as a race as some of Tamriel's greatest warriors.

http://elderscrolls.wikia.com/wiki/Orcs_(Skyrim)