Technically an orc from another brother. One theory was orcs doing the nasty with humans, think Treebeard said that in the book? Or them popping out of the ground via dark magic, according to Peter Jackson.

But I felt compelled to include him.

Tolkien was pretty loose with what an orc, goblin, and uruki-hai were. Lots of hints, but almost like he built them as an unsolved mystery on purpose?

I just decided to go with the first few pictures I could find that looked fitting. I should have included the animated LOTR/Hobbit (1970s) orcs. My personal favorites.