How about Mr. Smee, a rotund nincompoop First Mate of Hook with a jovial voice, but eager to abet the most heinous deeds on the excuse of Just Following Orders.
"Bowler Hat Guy" in Meet the Robinsons. He becomes dramatically more sympathetic further into the movie.
Megamind. You start to root for him since, despite his numerous failures against Boring Invincible Hero Metro Man, he never gives up. He always bounces back from his latest plot being foiled, ready to go at it again.
Films — Live-Action
Peter Lorre — as he was frequently typecast the "Sad Monster" after M — got to play quite a few of these in his career. Casablanca, The Maltese Falcon, Arsenic and Old Lace, and in pretty much all of his later career, particularly in his team-ups with Vincent Price.
On the other hand, Elisha Cook, Jr. made Peter Lorre look lucky. At least Lorre survived most of the above examples (and in Arsenic and Old Lace, he even pulled off a Karma Houdini). The same can't be said for poor Elisha in Phantom Lady, The Big Sleep, Born To Kill (where, shortly before his character's death, he tries to menace a little old lady, only to have the little old lady kick his ass!), or The Killing. In Shane, he's practically a good guy version of this trope. But the best example of how much worse off Cook is compared to Lorre is in The Maltese Falcon, where they're both ISVs. Sam Spade disarms and humiliates Cook's Wilmer far more often than he does Lorre's Joel Cairo, despite the fact that Wilmer's a multiple murderer and Cairo isn't. And at the end, their mutual boss (and possibly more) Casper Guttman sells out Wilmer to the authorities while happily walking off arm in arm with Cairo (although they all end up in jail). Joel Cairo may be more pathetic than you, but Wilmer is even more pathetic than Cairo.
Cook's character in House on Haunted Hill (1959), though hardly villainous, is quite ineffectual and sympathetic. He just had the right face for the part.
One critic said of Cook that 'his very appearance seems like an invitation to destroy him'.
Fortunately, things have turned around for him by the time he plays the mobster Icepick in Magnum, P.I..
Inspector Clouseau, originally intended as an incompetent version of Inspector Javert in the original The Pink Panther, managed to be so much more sympathetic than protagonist Charles "The Phantom" Lytton that he was retooled into the hero of the film's sequels.
In the following film, A Shot in the Dark, Clouseau transmitted this ISV condition to his boss, Chief Inspector Dreyfus (soon to become the former Chief Inspector Dreyfus). Dreyfus is actually a good detective who, it's implied, would never have gone Ax-Crazyif it hadn't been for Clouseau. After his Face-Heel Turn, poor Dreyfus has to look on helplessly as Clouseau survives all of Dreyfus' numerous murder attempts solely due to the dumbest of dumb luck.
And THEN, in Son of the Pink Panther, Dreyfus gets a reboot into sympathetic, if not protagonist, at least The Woobie status, as his complete descent into Axe Crazy has apparently been retconned out of existence and him back INTO existence. He even gets the girl with the down side of now being the stepfather to his late nemesis Clouseau's long-lost son. Still the Butt Monkey, if not the ISV.
Jerry Londegaard in Fargo. You can't help but feel something for him when you understand his situation, although, considering he did send two guys to murder his wife, he's not entirely sympathetic.
Vincent Price as Shelby Carpenter in Laura. This is how his own girlfriend sums him up:
"He's no good, but he's what I want. I'm not a nice person, Laura, and neither is he. He knows I know he's just what he is. He also knows that I don't care. We belong together because we're both weak and can't seem to help it. That's why I know he's capable of murder.note Keep in mind that she says he's capable of murder. He doesn't actually do it. He's like me."
Muerte ("name for death!") in Undercover Blues. Muerte's reputation on the streets is hinted at as being formidable, but his utterly humiliating defeat at the hands of Jeff Blue quickly turned him into one of these. Every lost tooth just makes him that much more lovable.