Recently we’ve had episodes featuring the return of Homer’s mom, Sideshow Bob, and Arty. Which character would you love to see again in a new episode?
I personally nominate Scorpio. Damn I loved that guy. He was the Best. Boss. Ever.
A very close second would be Homer’s half brother, Herb. Maybe we can have another episode inwhich Homer manages to ruin his life. 
I love Kelsey Grammar’s once a season (more or less) appearance as Sideshow Bob. The Sideshow Bob episode tends to be the one I look forward to the most.
I’d love to see another story centred around Selma as well. She has three really great episodes in the past, and I wish for more.
I’d wish the Sheri and Terri would get bigger roles as well, since they where essentially dropped as Bart’s nemesis (nemesii?) in the first season, they have pretty much been background filler, and I sort of miss their evilness.
In terms of a one off character… Hank Scorpio rules!
If I only had one vote it would go to Hank Scorpio.
Another suggestion would be Cecil. Although even though I loved “Brother from Another Sitcom.” I’m not sure there’s much else that can be done with him.
I want to see a Maggie main plot with the appearance of her apparent nemesis, the mono-brow (uni-brow?) baby.
His name was given once, by Major Quimby and hinting at some sinister circumstances. It may have been Huey (or rhyming with that).
Uni-browed baby is Gerald.
I have a soft spot for Duff Man.
Oh yeah!
Don’t forget that we got Dr. Marvin Monroe back after all these years. I’m not sure what you’d have Scorpio do for an encore, but he WAS really fun.
The two characters which I would most like to see would be Troy McClure and Lionel Hutz. Still so very sad.
I’d like to see more of Sideshow Mel.
Wait a second. Didn’t Dr. Monroe die some years back? Or was that just a joke? Anyhoo, if he did return, I missed it. Anyone care to tell me about it?
As for characters I’d like to see again, how about Shelbyville’s versions of Bart and Milhouse? Or that dream-guy of Lisa’s from West (East?) Springfield Elementary?
Anyhoo…
He did die and he did come back.
Marge makes reference to the fact in the episode. It’s not a very big part.
The tap-dancing lawyer who represented Manjula in her divorce from Apu seems like he was built for reappearances.
Also the monorail salesman… monorail salesman, we barely knew ye.
Handsome Pete who dances for nickels.
Jessica Lovejoy–the Bad Girl’s Bad Girl.
Bart needs a rival in mean-ness, & she’s the only good candidate.
Dr. Nick!
“The kneebone’s connected to the, something. The something’s connected to the, red thing. The red thing’s connected to my, wristwatch–uhoh!”
Another vote for Cecil. I have a thing for men named Cecil.
“HI, DOCTOR NICK!”
Lyle Lanley.
personally, I’d love to see more of Gill the inept salesman.
I’d like to see more of that crazy screaming lady who throws cats. I think there’s an untapped story goldmine there. 
Gill seems to have popped up a lot more in the last 2 seasons. I guess most of them are throw-away jokes though so I don’t know if they count.
Another vote for Hank Scorpio. I love that guy.
I’m going to have to agree with Hank Scorpio. He was a great character, and I’d love to see how they’d bring him back.
I’d also agree with Cecil. I love the interaction between him and Side Show Bob. Maybe they have Scorpio break out of jail with the Terwilliger brothers and try to take over the world again!
mmmmmmmmmmmm…World Domination…<drool>