This is an Orc.
Orcs only spawn in the dark, but they can survive in daylight.
When these mobs attack you, you will be set on fire so be careful with these. The danger with these mobs is high. However, there is also a good reward. When they die there is a chance that they will drop an Uruk Hai Sword which can be used to set other mobs on fire. There is no way to craft this weapon.