In 2868 one of Saruman's Hill-men spies captured a train of Orc slaves and brought them to Saruman as a prize. The Wizard was filled with loathing at the sight of them, but one Orc-slave knelt and kissed the stones at his feet and said in a halting voice.
Uruk-Hai were bred by Saruman in Isengard and were speculated to be the crossbreeding of Orcs and Men. That said, while he was shown to have a more hands-on approach with the Uruk-hai, he merely added to what was already created by Sauron.
Isengarders were the Orcs in Isengard who were in the service of Saruman. They were either bred by the wizard or they were recruited from the Orcs in the Misty Mountains.
It is recorded that Half-orcs came to be by an evil act of sorcery where Saruman bred Dunlendings with his Orcs. The evil Half-orcs were the result of this union. The Half-orcs were slant-eyed like Orcs, yet as tall as men.
In The Lord of the Rings movie trilogy by Peter Jackson, Saruman appeared to believe that the Uruks were his invention. In The Fellowship of the Ring, Gandalf mentions Saruman breeding the Uruks to possess the traits of "Orcs and goblin men" without the two races' weaknesses.
Allegedly, Tolkien originally toyed with the idea of making the Nazgûl afraid of the river as a result of being barred from crossing running water, which is an idea borrowed from classic folklore where evil things are unable to go across running water.
Yes, female orcs do exist in Middle-earth.
In a letter to one, Mrs Munby, JRR Tolkien wrote that female orcs do exist but that we've not seen them because they don't fight in Sauron's armies.
Half-Orcs, like most hybrid-species, generally are infertile, with some rare exceptions.
Orcs and humans have both held the Armlet of Strength and half-orcs are capable of interbreeding with both orcs and humans and continuing to produce fertile children. Interestingly, half-orcs like half-elves can also breed with other half-orcs and have created a fairly stable half-orcrace.
"Uruk" means "orc", and "hai" means "human". The Uruk-Hai are a cross between orc and man, and orcs are corrupted Elves. He already had the orcs on hand, and was going to win with them anyway. He didn't need the Uruk-Hai.
The wizard's own breeding of Orcs must have began at earliest around T.A. 2990 and these troops were kept in the muddy pits tunneled beneath Isengard in preparation for Saruman's attack on Rohan.
The first Dark Lord Melkor took hostage some Elves from Cuiviénen. He tortured them, beat them, and broke their bodies into the first deformed and twisted beings known as Orcs. Tolkien confirmed that female Orcs did exist.
The Uruk-hai are simple crossbreeds of human and orc, equivalent to a corrupted version of half-elves. There are two subspecies: Morgul Uruk-hai, bred by Morgoth and Sauron, similar to orcs but much larger and stronger.
Though Gimli has no children, he is not the last Dwarf of Middle-earth. After the fall of Sauron, his people continued to thrive in the Lonely Mountain. Gimli made his home in Rohan, in the Glittering Caves of Aglarond, and many of his kinsfolk came with him.
Saruman : Do you know how the Orcs first came into being? They were elves once, taken by the dark powers, tortured and mutilated. A ruined and terrible form of life.
There are actually a few sub-species of Orcs, including the Uruk-hai, who were stronger and were specifically created to be much better warriors than the Orcs that came before them.
Relationship with other Races
Half-orcs do not get along with much races. They rarely get along with elven races or dwarves due to the racial enmity between either and orcs. Halflings and gnomes do not trust half-orcs although they do not hate them as much as the elves and dwarves.
Age: Half-orcs mature a little faster than humans, reaching adulthood around age 14. They age noticeably faster and rarely live longer than 75 years. Alignment: Half-orcs inherit a tendency toward chaos from their orc parents and are not strongly inclined toward good.
Clearly, elves and humans may successfully interbreed, producing fertile half-elves in at least three documented unions (Idril and Tuor; Luthien and Beren; Arwen1 and Aragorn) (Tolkien 1955, Appendix A). Elrond the half-elven was the grandson of both Idril and Tuor as well as Luthien and Beren.
For elves and humans to be different species they must not produce fertile offspring. We know that half-elves are quite common but they can be interperated as hybrids, similar to mules or ligers, which are infertile.
Nearly all orcs have two pairs of tusks, one in the upper jaw and one in the lower jaw, although the lower tusks are much smaller and may be hidden by the lips, especially in female orcs. Tusks grow throughout an orc's life, and if broken off they will continue to grow.
offspring; therefore, Orcs and Elves can have fertile offspring. However, there are things called ring species (yes, really) where species A can mate with B, and B can mate with C, but C cannot mate with A.
Elves view the sexual act as special and intimate, for it leads to the birth of children. Elves who are married cannot be forced by other Elves to have sex; before that they will lose the will to endure and go to Mandos. Elves have few children, and there are long intervals between each child.
As such, the Orcs were literally born in the dark, fighting and thriving in the black of night. When the sun rose over Middle-earth for the first time years after their initial creation, the light traumatized the Orcs, burning and blinding them after so many years shrouded in darkness.
Despite the common belief of all orcs having severe underbites, they most likely have well-aligned teeth with the upper teeth fitting slightly over the non-tusk lower teeth. This is thanks to the unique angle of the tusks, which grow straight out before growing upwards.