Orcs are one of Tolkien's most famous creations, and hold a place in nearly all modern fantasy adventures. In The Lord of the Rings Orcs are the soldiers of the enemy – namely Saruman and Souron, although they do exist in other parts of Middle Earth. How they were created is not clear, Tolkien made out in the Silmarillion that Morgoth ensalved Elves, hence creating the Orc. Other notes by Tolkien suggest that these evil minions were simply created by Morgoth's evil essence and being, as a mockery of the Eldar. In the films it is unclear also from whence they originated, but there are scenes which show Saruman in 'spawning pits' where he orders his minions to dig up newborn Orcs.
In nature the Orc is portrayed as evil, for most of the books, and the entirety of the films. However strangely enough in The Two Towers when Sam overhears two inhabitants of Cirith Ungol talk the reader is given an impression that Orcs are quite human in nature, as these two mention 'settling down with the boys' in some distant corner of Middle Earth. Nonetheless they serve their evil masters endlessly, killing innocents countless times and destroying all the pure things in the land. Physically these dark minions are quite similar to Men, only shorter; they are strong and stout, with blackened skin. There are various breed of Orc, each with it's own differing physical traits, such as the Uruk Hai which are much stronger and larger than the standard of their kind. In combat they are feirce, but seem to be no match for Men or Elves, as 300 Rohan hold against 10,000 Uruks in the second book.