I was contemplating the OT a while back when it struck me how underappreciated Jabba the Hutt is. He's a horrid slug, but he also provides a way for the rest of the characters to reveal their motives and personalities and keeps the plot moving through all three movies.

In A New Hope, Jabba is just a name (in the 1977 release, anyway). But his is an important name, and an ominous one. First, Jabba helps Luke and the gang get to the Death Star: the whole reason Han Solo and Chewbacca are desperate enough to become a flying taxi service for a farmboy, an old man, and two droids is because they need to pay Jabba back. If they weren't broke, or if Jabba wasn't enough of a threat that they actually needed to pay him back, they might not have been in the cantina at all, and so Obiwan would have had to find different pilots. Just try to imagine Star Wars without Han and Chewie! The fact that they ever worked for Jabba in the first place is also a reflection on their characters. Next, Jabba (by proxy) enables Han Solo to really show what kind of guy he is: the bounty hunter Greedo arrives intending to capture or kill Han and take him to Jabba for a reward, and Han coolly readies his blaster while keeping Greedo distracted and then blasts the bounty hunter into charcoal. (Again, in the original release.) Once the characters have arrived on Yavin, Jabba again makes his presence important: instead of joining the Death Star attack, Han takes off to repay Jabba. Not having the Millenium Falcon and her skilled pilots throughout the battle makes the Rebels that much more of the underdogs. It also shows Han's priorities in life, and makes his decision to return much more powerful than if he had never left. Finally, Jabba provides a second link between ANH and its sequel: the first is, of course, the continued menace of the Empire, and the second is the looming threat over Han's life. Greedo told him that Jabba would put a price on his head so large that every bounty hunter would be after him, and as he has not payed Jabba by the end of the movie, we are still waiting for that shoe to drop.

And it does. The Empire Strikes Back starts with the Imperial threat in the form of the probe droid, but it quickly picks up the Jabba plotline: "That bounty hunter on Ord Mantell" changed Han's mind about staying with the Rebellion, and he is once again about to leave to pay the crime lord back. He is delayed when he rushes out into the blizzard to search for Luke, however. The real and dangerous threat of Jabba looming over Han means that he is actually risking his life twice, in the blizzard and in the future by delaying the payment yet again. It also reveals Han's slowly changing priorities--his friend is now his most important consideration. Next, the Jabba plot joins with the Empire plot, uniting the threats to the heroes: Vader hires bounty hunters to catch the Falcon and her crew, and Boba Fett gets to keep Han (despite his possible value to the Empire--he has been hanging out with two of the Rebellion's leaders and the last Jedi trainee for three years, after all) to give to Jabba. The realization that she is about to lose Han spurs Leia to finally admit her love for him. And finally, Han's imprisonment in carbonite is a huge cliffhanger drawing us into the next movie.

In Return of the Jedi, Jabba finally appears onscreen. He's big, he's revolting, and he is very powerful: get on his nerves even a little bit and you're rancor food. He is also immune to the Jedi mind trick. Clearly, the heroes can't just charge in without a plan like they did on the Death Star. And they don't. This rescue mission gives the characters a chance to show how they've grown over the last four years--and a chance to practice before they go up agains the ultimate adversary, the Empire. The rescue mission is Luke's first appearance as a calm, confident, really powerful near-Jedi: he shows he can not only keep his fear and anger in check, but that now he can organize and think ahead much more than he could even a year ago. Leia shows off her skills as well: we knew she was a good shot, but now she's also a master of disguise, a cool bluffer (the thermal detonater trick worked a lot better than her denial of involvement in the Rebellion in ANH), and incredibly strong--strangling a Hutt as fat as Jabba is no easy business. Without Jabba, we would never have seen so much of this side of her. Lando redeems himself on this mission enough so that he has our support when he joins the Rebellion instead of our suspicion. (His reversal at the end of ESB wasn't enough.) Artoo gets to save the day yet again, and Threepio gets to practice translating under pressure before he meets the Ewoks. Han realizes that his friends really do care about him and won't abandon him, which seems to finally dissolve the bulk of his cynicism; it is after this mission that he finally joins the Rebellion officially, setting the stage for the final battle against the Empire.

Character-developer, plot-mover, training for the really important fight--Jabba sure does a lot, doesn't he?