Wow, the title threatens to be longer than the body of the post, huh? Kinda like that Fiona Apple album from the late 90s with the ridiculously long name.
Anyway, I'm sure you have this syndrome, too. You'll be watching a movie, and for whatever reason, you really start to sympathize (or hell, empathize) with a secondary character. I figured I'd call attention to the ones I've always felt really bad for. Obviously there might be spoilers here, so read at your own risk.
10. Sallah/Marcus Brody in Indiana Jones and the Last Crusade. They barely make the list 
because my reasons for feeling bad for the characters isn't story related, it stems from poor characterization continuity. Both of these characters change drastically from Raiders of the Lost Ark. Both are relatively dignified in Raiders, Marcus especially so. In Last Crusade they are both turned in to clown shoes for comic relief. For shame.
9. Ross on Friends. This is a bit of a stretch since its hard to call any of the main cast of Friends "secondary" but indulge me that on any given episode, given the ensemble nature, any of them can take secondary roles. He's not always right, but the show does a fairly good job of making him the brunt of most of the jokes. Almost every altercation he has with Phoebe is a great example of how being "cruel to Ross" is funny in their world, but the example I'll give is when Ross and Phoebe debate evolutionary theory. Ross, being a doctor of paleontology, of course believes in evolutionary theory, but Phoebe doesn't prescribe to any one course. By the end of the show, she gets Ross to admit that there is the possibility he might be wrong since so many theories have been disproved in the scientific world over the course of human history. When he does reluctantly concede that she has a point there, she mocks him for "caving" on his beliefs to the "entertainment" of the audience. Man, I simply feel bad for the guy at those points.
8. Bishop in Aliens. He gets pissed all over by Ripley the entire movie for her (justifiable) fear of artificial life forms, but he's nothing but virtuous, even embarking on the very dangerous mission to remotely fly the second drop ship down so they can get the hell off that rock. He comes through and right after Ripley FINALLY gives him respect, he gets bisected by the Queen. Rough gig. Honorable mention: Newt and Hicks...mainly because Aliens goes out of its way to have these two survive only to have them unceremoniously offed before Aliens3 ever really starts. Booo!
7. Bob Morton in Robocop. Okay, he's an asshole...but he's not as big of an asshole as Dick Jones
or Clarence Boddicker, and he did conceptualize Robocop. This is the guy who thought up the whole Robocop idea, and he's grenaded to bits by Boddicker, because he dared to make Jones look bad when ED209 malfunctioned and talk some shit in the executive washroom at OCP. In a way, Murphy doesn't only avenge his own execution by Boddicker and his gang, but his creator's execution.
6. Every person caught in the crossfire of every 80s action movie ever. Seriously, watch an 80s (and sometimes 90s) action movie, and there'll be some poor schmuck standing in the wrong place at the wrong time. Heck, I think in Total Recall Arnie uses one as a human shield once they've been killed. Unceremonious!
5. That lady Marcellus Wallace shoots because he's wobbly from the car accident in Pulp Fiction. I mean, come on, even in a movie full of gratuitous violence, was it necessary for her to take a round in the leg for trying to be a good Samaritan? I always cringe at that scene, moreso than the "needle in the chest" scene.
4. Frank Poole in 2001: A Space Oddysey. Poor bastard never saw it coming, did he? And here's an even worse scenerio...what if HAL didn't kill him initially by slamming the pod in to him? That means he ends up starving to death in his space suit, floating in the vast depthness of space. Shudder.
3. Cicero in Gladiator. Who, you're probably asking? Maximus' aide, the one with the scars. OH THAT GUY you're saying. Yeah, him. Poor guy. He gets about 5 minutes of screen time. He gets to talk to Maximus right before he's betrayed...gets to find Maximus at the Colliseum, and then deliver his figurines and ring to him, then he gets to talk to Lucilla for about a hot second, then, for all his faithfulness he gets hung AND hit with like a dozen arrows.
2. Mouse in the Matrix. I just feel bad for the little guy. He seems so...chipper...for a guy in their
relatively bleak situation and he gets offed relatively unceremoniously. I also feel fairly bad for Apoc and Switch in that regard, but at least they don't seem quite as full of life as Mouse did, although they do go out with more of a whimper than Mouse...Mouse at least gets a warriors death.
1. The Mother in Big. Seriously...everytime I watch Big all that I can think of is "jeez, the mother really gets screwed here...thinks her boy is kidnapped for at least a couple months and then bammo, he's home again, and he's not going to be able to give any real coherent story to his whereabouts or kidnappers so she can have justice or closure. That poor woman. Plus, her son lost his virginity at 12...technically.
