Here's to Billie the lady slayer.

Instagram may have a new dynamic duo on its hands. While answering fans' questions on her Instagram story on Wednesday, Billie Eilish revealed her childhood celebrity crush: Sarah Michelle Gellar in her iconic role in Buffy the Vampire Slayer.

When the 20-year-old Grammy and Oscar winner was born, Buffy had already been dead for 147 days and resurrected. Season 6 was in full swing, and Gellar had already graced three covers of Entertainment Weekly. But you know, age is just a number.

After Gellar caught wind of Eilish's love for her, she gushed in an Instagram post featuring the singer's story.

"I'm dead. That's all," the 45-year-old actress wrote. "I'm not a child anymore, but I totally have a crush on @billieeilish Ok… now that's really all."

Other celebrities echoed Eilish's sentiments in Gellar's comments section, with To All the Boys' Jordan Fisher admitting, "Ohhhhh I never told you you were one of mine."

The interactions didn't stop there. When Eilish saw that the actress acknowledged and reciprocated her feelings, she wrote in her Instagram story, "Um oh my god." 

Sarah Michelle Gellar; Billie Eilish
Sarah Michelle Gellar; Billie Eilish
| Credit: Jon Kopaloff/WireImage; Jeff Kravitz/FilmMagic

SMG had another cause for celebration this month when she feted her birthday with a mini Cruel Intentions cast reunion with her pals Selma Blair and Ryan Phillippe in front of a cheeky painting depicting Phillipe's famous butt scene from the teen classic.

As for Gellar and Eilish's mutual affection for one another? All we're gonna say is… Freddie Prinze Jr., watch your back.

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