here's my list

grade level: high school

Worsest : Witch (most basic costume too plain)
Best : Oompa-Loompa (from Willy Wonka, looks exactly like one, and he's also short.)
Worsest is not a word.

Grade : High School
Worst : Me, going to a party as ME with werewolf gloves.
Best : Edman! Ed (my nextdoor neighbour) put on a black bin liner and EDMAN was formed!

In response to Ease
Im 13......I still go trick-or-treating, but I don't dress up. I dyed my hair and put some blood on my face.....and that was it. I hit every house in a 100+ house..... I dunno, development? There were about 25 way up on the hills, and no one was going there so those people gave me like 15 pieces each.
I'm 18 but we still do stuff like this for school, it's just plain fun to dress up for halloween and spirit week. After all, holidays like this is just another reason to have fun.
I took a cotton ball, dipped it in black paint and let it dry at night after I molded it a bit, In the morning I put it on my chin as one of those evil goatees and went as the Evil me. I had a friend from saratoga who went as jesus, that was pretty neat. My favorite costume I witnessed was my girlfriend's brother's warewolf costume, he looked really believable and had hand/feet shackles and everything.
Who says halloween is for younger people?

I put on a muscle man upper-body shirt with huge pillowy muscles. Pretty good time at school seeing everybody elses costumes though.
In response to NeoHaxor
NeoHaxor wrote:
evil goatees and went as the Evil me.

We don't have Halloween in Australia, but I do that all the time anyway. =P I'm "lucky" enough to be gifted in the facial hair area enough to grow a decent bizaro goatee pretty fast.
I like to go one step beyond just a goatee and wear all white (I usually wear black to grey), spray my hair white, and do the neat version of my hair.
I really want to start getting white or blue contact lenses, but I've told that would cross the line between goofy and insane.
You should give it a try on New Years Eve, the first day back at school, or stupid-pranka-poluzaa-poluzaa (Aka, every Tuesday).
Halloween is for kids, every other day is for idiots... I really wish we had Halloween here...