Interrogation Droid

The Interrogation Droid vanity pet can be bought from the dark side vendor, Lord Davorak on the Imperial Fleet or Vindir on the Republic Fleet, for 25,000 credits.  They can be found in the Galactic Trade Market-section on the Imperial Fleet. You have to be at least level 3 dark to be able to buy it.

Once out it looks like this:

Little Sandcrawler

The Little Sandcrawler vanity pet can be bought from the light side vendor, Lord Vassanar on the Imperial Fleet or Mira on the Republic Fleet, for 25,000 credits. They live in the Galactic Trade Market-section. You need to be at least level 3 light to use it.

Once out, the sandcrawler looks like this: