“Am I unicorn? Am I mermaid? Am I part showgirl?!? Whatever I may be, I’m ready to support my favorite charity @goodplusfdn (oh yeah and I love Halloween) Thanks @deleonmakeup and @alisherry - I am even rocking my @Foodstirs spoon necklace that benefits #goodplusfoundation,” she captioned the shot.
Gellar sported the look to attend the GOOD + Foundation Halloween Bash in Culver City, Calif.
ET caught up with the star at the event where she opened up about her wild makeup.
"It takes a minute," she joked to ET's Katie Krause.
She went on to talk about her involvement in the foundation.
"I have been working for a year on this event. We started planning it the day after last year’s," she said.
"So last year was our first year and we exceeded expectations and then this year we’ve already blown past expectations. It’s just such a great way to help out a charity that’s so near and dear to my heart at the same time have the spirit and fun of Halloween."