I had a dementor costume that I really liked. Other than that nothing stood out. I stopped trick or treating after 4th grade and I don't think I have dressed up since 6th.
I don't remember any of this, but apparently when I was six, I wore a red fringed dress and a headdress and won a competition with it.
If you're counting the past few years, I found this marvelous black cloak that allows me to be Death, No-Face, a ninja, and much more. Black cloak is the best halloween costume.
I had lots of costumes over the years. A monkey, a mouse(I was very young.), Darth Vader. But the costume I loved the most as a kid was this skeleton costume with a light up skull mask. It was really cool, and being in first grade, all of the kids were in awe of the mask.