The 'Buffy the Vampire Slayer' star fangirled over the moment.
On Wednesday, Gellar shared a picture of a screenshot from Eilish's Q&A.
During the session, the 20-year-old GRAMMY winner was asked, “Who’s your childhood celebrity crush?” Eilish responded with a photo of Gellar from her hit ‘90s series, Buffy the Vampire Slayer.
Gellar captioned the post, “I’m dead. That’s all. I’m not a child anymore, but I totally have a crush on @billieeilish Ok… now that’s really all.”
While the pop star didn’t respond to the post, Gellar quickly found out that Eilish wasn’t the only one smitten with her.
“ohhhhh i never told you you were one of mine 🤣💜,” Jordan Fisher wrote.
“Hahaha love it,” Amanda Kloots wrote.
Gellar has been married to fellow actor Freddie Prinze Jr. since 2002. The pair are parents to Charlotte, 12, and 9-year-old Rocky.
The actress isn’t just feeling the love from Eilish. In March, the cast celebrated the 25th anniversary of the series, which ran from 1997-2002, and Gellar celebrated the moment on Instagram with a throwback.
"25 years ago today I had the honor to introduce the world to my version of Buffy Anne Summers,” she wrote. “It was an uphill battle. A mid season replacement, on a new network based on a movie, that was by no means a giant success. But then there was you. The fans. You believed in us. You made this happen. You are the reason 25 years later we are still celebrating. So today we celebrate you as well. #wwbd."
In July, the star spoke with ET about her children finally being introduced to the teen vampire slayer. "My boy was into it for the villains, and my daughter was into it for the love stories," Gellar shared.