If your Declared Imperial and have the faction points to buy them, you get Stormtroopers or even AT-STs. They are called Faction Pets. Depending on your Rank you can have up to 3 out at a time.
Rebels get Marines and Commandos as faction pets
Master Creature Handler, could have 3 AT-STs, 3 Pets, and a Droid out at the same time.
Edited, Tue Jan 20 10:17:12 2004 by Oloth