Like the title says. It can be a costume that a hero already has, something inspired by their other properties, or something that Blizz probably can’t do due to copyright.
I’d love to get a Moira skin inspired by Shadow Priests from WoW or a Mercy skin that’s inspired by Auriel from Diablo or the Spirit Healer in WoW. A Doctor Who Tracer skin would be really fun too.
The Diablo Junkrat skin from HotS
Mercy as a holy blood elf priest, Moira as a night borne shadow priest, Roadhog as an abomination.
Jeff Kaplan skin for Torbjorn.
Mercy with just a sheet over her, so you see a lame looking ghost flying all over the map.
Scooby-Doo sound effects while she flies around.
Give Reaper a real vampire skin. That would be better than the alien head skin they call “Vampire.” Give Reaper a real demon skin, or at least a legendary version of it. Give Reaper a real biker skin. Not biker, but biker biker. You know? The bikers who ride motorcycles, not dirt bikes. Give Reaper a real Los Muertos skin. Glowing paint or bust. Get rid of the ukulele too. Give Reaper a real plague doctor skin, make it more steampunk. Yeah? Oh, and give Reaper a real Reaper skin.
Other than that, his skins are perfect. If I had to pick just one, I would pick them all. 
I would also like this. Or any sort of sorceress skin for her or symmetra. But she already has the magician skin which is dope.
Plus with Moira, we would have the triple magic users: witch mercy, magician symmetra, sorceress moira.
Also: Alchemist Ana PLEASE Blizz! She’s already an alchemist in Junkenstein’s revenge JUST DO IT!
And of course (not really halloween) but Thanos Doomfist!! It doesnt have to be precise, I’m happy with just a gauntlet with cool jewels on it
A werewolf skin for Tracer, it would fit pretty well
You might wanna change it from “just a sheet”.
I would say a Demoness/Succubus outfit for the ladies and a Demon Lord outfit for the guys.
Mercy’s Demon skin is a joke, she needs a proper outfit for it.
Brigitte in a Joan of Arc skin?
Are you trying to infer something from nothing? Because that’s what it sounds like.
a human skin for bastion and zen
Werewolf Zarya would be great.
And when she’s on fire…what voice line would she throw out?
I would want ghost tracer.
That with her “boo!” voiceline would be glorious.
“Anybody have a stake?”
Id love a halloween skin for D.va where she is a witch that flies around in a giant pumpkin
I just want Sombra in normal casual clothes, no additional wires or anything, imagine how cool it’d be, she would look like a completely normal girl, but have all those cool abilities.