Today I'm checking out a type of costume called Creature Reacher - They're extra scary due to the oversized masks and gigantic latex hands you wear over your own hands. I've never actually seen anyone wear these in person - perhaps people were showing restraint, as the parties I've been going to in past years were for very small children?
The Grim Reaper costume looks pretty comfy to wear (other than the outsized head and hands). Basically it's a robe, and you just throw it on top of some black pants, kick on some black shoes, and go off on your merry way to terrorize neighborhood children. (It's also in stock on Amazon).
In case he isn't reapery enough for you, here's the Grand Reaper costume.
I don't think all that many people are actually really terrifed of clowns. It's just trendy to say that you are. Still, this Creature Reacher clown costume is pretty frightening! Also available on Amazon.
You could be offering huge buckets of my favorite Halloween candy (Baby Ruths) and I wouldn't be able to stop myself from running away from your front doorstep if you opened your front door wearing this Shady Slim costume! It's also sold on Amazon.
Does this scarecrow kind of look like Gandalf to you too?