Alyson Hannigan Sparks Impromptu ‘Buffy’ Reunion On Her 40th Birthday

Alyson Hannigan spent her 40th birthday catching up with an old friend from Buffy The Vampire Slayer.

The actress who played Willow on the cult favorite series tweeted her surprise about turning the big 4-0, and got a response from her former co-star Sarah Michelle Gellar.

“That’s not possible. It’s just not,” Gellar tweeted in reply. “You are confused by your daughters birthday. Happy Birthday to you both.”

The mini Buffy reunion was a hit with fans, many of whom suggested the show take a page out of the Veronica Mars playbook and spin off into a movie (despite the fact that the Buffy television series was already based on a movie).

While Alyson Hannigan is recalling one of her most-loved characters, the current chapter of her acting career is about to come to a close. For the past nine season she has played faithful friend Lily on How I Met Your Mother, but the show will air its series finale on Monday.

Though rumors have abounded about what direction the finale could take — and whether the titular mother might actually be dead at the time the story is being told, roughly 20 years in the future — Hannigan isn’t giving too much away.

She did say it would be a satisfying conclusion, however.

“I think the writers really wrap the show up the way the fans would want it to be wrapped up,” she told Jimmy Kimmel in an interview on Monday. “They’re going to answer all the million questions that everybody has and more.”

Alyson Hannigan admitted it was very emotional seeing the series come to an end.

“It was [sad]. I killed a lot of trees with my crying,” she said. “The last table read… we all do love each other so much and I would say 99% of the room was crying – and that’s executives and everything.”

Fans can catch Alyson Hannigan in the How I Met Your Mother series finale on Monday, but Buffy fans hoping for a real reunion may be out of luck.