Orc Breeds.

Here's all the Orc breeds (or perhaps some of them are actually tribes,it's not always easy to tell) I can think of, apart from the unnamed "smaller breeds" mentioned in chapter two of book six.

Uruk-hai. Also called Uruks and black orcs.

Orcs of the Mountains. Also called Northerners.

Orcs of Mordor. Also called Orcs of The Eye.

Morgul Orcs. I don't think these guys were much different to the Orcs of Mordor, although they did have better gear.

Trackers.

Can anyone think of any others? One of the things I like most about LoTR is the way Tolkien characterised the Orcs. They are both amusing and brutal at the same time.