The Empire is a common trope. When it decays, it is a Vestigial Empire. An empire during its formation, in its expansionist stage, is a Rising Empire. Typically it will be a Proud Warrior Race, a Proud Merchant Race or both that is feeling its oats and beginning several generations of conquest, exploration and colonization. Likely it will have The Conqueror at its head, perhaps a Young Conqueror or a Galactic Conqueror. Examples of Rising Empire include: