The Orcish Species consists of three subspecies; the most common, Orcius Orcius, is also known as the commmon Orc; next is the more evolved Orcius Goblinus, or Goblin; finally there is the now rare Orcius Trollus, know called the Troll or Bridge Troll.
Orcius Orcius was the first created by the evil wizard Mondain during the First Age of Darkness as a cross between a human and a dog. These vile creatures bred rapidly and could be easily created by sorcerous means. Orcs comprised the bulk of Mondain's army, and after his defeat most of the Orcs flocked to the banner of his consort Minax, once she had herself mastered the art of creating these mockeries of life. Building upon the "success" of the Orcs, Mondain further corrupted and mutated these creatures into Orcius Golbinus, a stronger and somewhat more intelligent version of their Orcish cousins. Goblins were capable of simple speech, and were capable of rational, though evil-minded, thought. They took considerably more effort to create than orcs, however, so they were seen in fewer numbers. Finally Mondain created the Orcius Trollus, or Troll. This was by far the most difficult and straining to create, as can be gleaned from the sorceror's journals. Though more stupid than even the Orcs, Trolls posessed the strength of ten men, and had skin tougher than iron.
The existance of Goblins and Trolls on other planes of existance has led some to specualte that perhaps Mondain learned the secret of their creation from one of his otherworldly contacts, and the Orc was his first, flawed attempt at creating goblins. However they were created, they played a major role in the Age of Darkness and the reign of the Triad of Evil. After Mondain's death, the Orcs fled to the dungeons until Minax proved herself as their master by mastering the creation of Orcs herself. However the complete and utter defeat of the Dark Enchantress almost brought about the end of the Orcs as well, countless numbers being lost in time. With the Orcs all but vanquished peace seemed near, but then the Hellspawn Exodus appeared, whose sheer magical power approached that of his 'father' but who was much more methodical and efficient, bringing all of the Orcish populations higher than they had ever been.
At first these creatures were held together by magic, but after they were separated from their Dark Masters, subsequent generations became less and less bound by the magic until they were at last a natural creature. When still magically bound, that is up to the destruction of Exodus, they were susceptible to dispelling magiks such as the priest spell 'Repond' used greatly during the Third Age of Darkness.
Exodus was the last of the great powers to create these monstrosities, as did Mondain and Minax before him. After his destruction at the hands of the Hero, the Orcs, Goblins, and Trolls, deprived of leadership, took refuge in the dark recesses of the dungeons, or formed roving bands of marauders that waylaid travellers in the uncharted wilderness. Eventually they became naturalized, and the Orcs and Trolls reverted to a more animal state, appearing more as ravenous dogs than magical beasts. The Goblins, retaining much of their intelligence, fled underground, and besides their role in the failed Stygian Abyss colony, and occasional sightings in the sewers, they are rarely seen today. The Trolls, hunted by increasingly brave knights, withdrew to the deeper parts of the earth as well, though some began to congregate beneath bridges, suprising unwary travellers and extracting payment from them. By the end of the Age of the False Prophet, the common Orc was all but extinct, shunning light entirely, and their cousins the Trolls fared little better. Only the brute strength of the Troll has kept it alive, and some have found employment as hired muscle among the shadier humans. Some still haunt the bridges and dungeons, but the Trolls seem to be slowly going the way of their brethren.
All of this is not so throught the multiverse, as recent expeditions by the Avatar and the companions have proved. Goblins seem to be found in much greater numbers than in Brittania, especially in the Serpent Isle, which was once, before the death of Mondain, attached to our own continent of Brittania. One interesting point is that the Serpent Isle seems totally devoid of Orcs, once the most populous of the Orcish Species. The explanation is that they were also the most reliant upon their masters, as can be seen by examining their current status in Brittania. Without the presence of Minax and Exodus, who appeared in Brittania but not the Serpent Isle, the Orcs there would most certainly die out.
Other, seemingly unconnected planes, share a common tie, Goblins, and to some extent Trolls. Information gathered from the Avatar after his journies through the Blackrock Gem have revealed a huge number of diverse realities that contain Goblins, strengthening the theory stated above that Mondain obtained the formulae for the creation of the Goblins from sorcerors in other worlds. In addition, it seems the name of our late resident archmage, Mondain, is known in other worlds as well.