“Look at the Gondorians, the Númenoreans. They build things. If the Orcs are ever going to have a future, we have to build it. I'm talking buildings. Mortar and bone and steel.”— Ar-Kaius the Architect
Ar-Kaius, also known as the Architect, was an Olog-Hai who focused on making new industrial creations, willing to ally with anyone who supports with his quest. Throughout his glorious mission, he has made an enemy out of an Uruk known as the Digger who shares his underground domain with Ghûls. Ar-Kaius's ego is only matched by his immense size and isn't hesitant to take credit for the construction of other fortresses such as those of the Marauder Tribe, Machine Tribe, and even Sauron's abode of Barad-dûr itself, except for the citadels of the Outlaw Tribe for he thinks of them as worthless. While his actual deeds of making strong forts are well-known, so too is his main weapon of choice, the iconic hammer dubbed "Boneshaker", which he uses for both battling his allies' foes and for fulfilling his vision of a grand future for Mordor.
- Ar-Kaius is modeled after Leonardo da Vinci.