Fat Boy - A massive rolling fortress and factory from Supreme Commander
These bad (and fat) boys roll around at two miles per hour and are equipped with 12 battleship tier guns, 2 anti air cannons and have the ability to create any unit they want to in a short time..
Did I also mention it has a shield generator, can go underwater and can dock air craft on its roof..
The only thing that can stop these beasts is strategic bombers or well calculated artillery..
And of course the horrible spam technique..