But Hannigan, 43, married to fellow Buffy star Alexis Denisof since 2003 and mum to daughters Satyana, 8 and Keeva, 5, is more than happy to regale fans with tales of her time on Buffy, as well as How I Met Your Mother, at Oz Comic-Con in Melbourne on July 1-2.
Q: What do you love about conventions?
A: I love the Q&As because it sort of does trigger memories, especially being with Tommy [Lenk], too, because he and I are two peas in a pod. He was a light in a dark tunnel on those, 'OK, it's three am and we're in a graveyard on a Friday night. Where's Tommy? We need some entertainment!' So it was always good laughs. I love meeting fans. I am very aware of, 'I have to meet everyone but I can't be here for one hour for one person,' but I love it and it's just so cool to at least take pictures or have a couple minutes with them to talk.
Q: Are your girls into Buffy or are they too young yet for the series?
A: Yes, too young, too young. Even if I worked on it, I think they would still be too young. I think seeing their mother turn evil would probably traumatise them for awhile, so they are going to have to be a lot older. Maybe I could play the first couple of seasons, but not right now.
Q: You've come back to the American Pie franchise. Would you do the same if How I Met Your Mother or Buffy called?
A: Definitely, yeah. Yes, absolutely. How I Met Your Mother would be the ideal one because it was just a fun experience and the group just, it was just fantastic, so that would be the ideal job to come back. Buffy, I don't hold up hope because so many other cast members said they wouldn't do it or Joss Whedon, and obviously nobody would want to do it without Joss, so that is not going to happen, but never say never. And who knows? American Pie: Old Age Home could be funny!
Q: You got to play Lily Aldrin for nine seasons, another longtime character as you had with Willow. What do you imagine for Lily Aldrin now?
A: I just loved being part of Lily and Marshall and their relationship. It was so much fun. Jason [Segel] and I would joke that we should do the spin-off of just them and call it Out By Lunch, because he and I worked so well that when it was days where it was scenes between just the two of us, we would be done before lunch and the crew loved it, so that's what our spin-off was going to be called. It was a real pleasure to get to do scenes with him. He's such a wonderful guy and it was just a great experience.
Q: With those great experiences you've had, does that give you a better focus of what roles you want to take on next?
A: I mean it definitely makes me, I guess, more picky, because I've been spoiled. It's harder to find anything I want to do because I've been so fortunate to have such incredible writing, so I'm probably too choosy, but also my kids are growing up like weeds and it's been really nice to be a full-time mom, part-time actor so I don't miss this small window when they actually want me around. Very soon, I'll just be the chauffeur, like, 'Drop me off here and pretend you don't know me.' I'm sure that day is coming far too soon, so I'm just enjoying every moment that they still want me.
To read more from Alyson, including what she geeks out about and what she sees in her daughters' futures, pick up the latest issue of WHO on newsstands now.