Is that Jabba’s Rancor!?

Yes, that’s a rancor. Now, it could just be a random rancor, as these creatures often appear in games and comics as large, deadly enemies for our heroes to defeat.
But considering the time period of the game—it’s set before Return of the Jedi—and Outlaws’ focus on criminals, I think this could be Jabba’s rancor. It looks a lot like it, and the area it’s in seems similar to the dark pit we first see it in during Return of the Jedi. If so, you’ll be unable to kill it, as Luke does that in the movie.