The game Supreme Commander developed by Gas Powered Games and published by THQ is considered by many to be the "Spiritual Successor" of the cult classic Total Annihilation. The game features units of different sizes, though what we will be focusing on are the end game behemoths. So far, three large units have managed to catch our (and IGN's) attention.

Armored Command Unit (ACU):
The ACU serves as a command center, barracks, and upgrade hub all in one giant package of pwnage. The scary thing is, you can actually use this as a mobile weapon of destruction once it's been upgraded. After undergoing the multiple upgrades at its disposal, this baby can actually dominate a map when used with the proper support units.

Possible Upgrades

Submersible Aircraft Carrier

Strategic Artillery

Mobile Factory