1. Scooby Doo 
2. M&Ms
3. Schuyler Sisters 
4. Pacman 
5. Three Pigs
6. Social Media Shirts with Tutus
7. The Golden Girls
8. Disney Villains
9. Inflatable Tube Man Dancers
10. Ghostbusters
11. Hippies
12. Clueless
13. Hocus Pocus
14. Frat Boys
15. Crayons

Cites:

https://www.google.com/search?q=halloween&rlz=1CAHZJV_enUS862&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiKtfyMp4HzAhUMkWoFHeHoD4AQ_AUoAnoECAIQBA&biw=1366&bih=617&safe=active&ssui=on