In the Forgotten Realms campaign setting for the Dungeons & Dragons role-playing game, a Tanarukk (plainly a portmanteau of "Tanar'ri" and "Uruk") is an orc with some degree of evil outsider blood, in most cases but not restricted to that of a tanar'ri (demon). They appear as short, stocky orcs with short bristly hair and horns or ridges along the sides of their heads. Tanarukks have a distinctive smell of brimstone about them and have the limited ability to manipulate fire.
The Tanarukka originated as orc-demon crossbreeds in the region around Hellgate Keep/Ascalhorn. However, years of dwelling on Faerûn has led to their being regarded as a separate species, rather than simply as tieflings. They're nasty, brutish and short, as the saying goes, and not necessarily terribly blessed with intelligence. They are, however, extremely dangerous fighters. They can often be found acting as muscle for cambions and other fiend-related creatures.
Tanarukka first appeared in Hellgate Keep, a module by Steven E. Schend, and subsequently in the Monsters of Faerûn supplement. The book Races of Faerun contains a v3.5 update stating that Tanarukk count as being both "native outsiders" and "orcs" for rules purposes.