Popsugar Entertainment Halloween Once Upon a Time Costumes For Halloween 10 Fairy-Tale-Perfect Once Upon a Time Halloween Costume Ideas October 31, 2018 by Kelsie Gibson View On One Page Photo 10 of 11 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 10 Zelena What to wear: Similar to Regina, you should opt for a fancy black dress, with just hints of emerald green in your accessories. Don't forget a structured hat to top the whole look off. How to act: Completely wicked and occasionally green with envy. Previous Next Start Slideshow HalloweenOnce Upon A TimeHalloween CostumesGroup Halloween CostumesPop Culture Halloween CostumesTVDisney Halloween Costumes