SAN DIEGO - As "Xena" and "Spartacus" fans already know, Lucy Lawless is a badass - so it should come as no surprise that the actress will be carrying on that tradition in her new role as Isabelle Hartley on "Marvel's Agents of S.H.I.E.L.D."

"[She's] a SHIELD agent, longtime SHIELD agent, so she has a history with Coulson," said S.H.I.E.L.D. co-creator Maurissa Tancheon while promoting Season 2 of the series at San Diego Comic-Con. "She's great, she's badass, she's everything that we love [about] Lucy Lawless. We've been huge fans of hers and we worked with her on 'Spartacus,' so we're just thrilled that she's joining us."

Added Tancheon's partner-in-crime Jed Whedon: "She'll fit right in."

As for the series' rather shaky beginnings, the duo have no doubt that tie-ins with the Marvel Cinematic Universe later on in Season 1 helped generate goodwill from fans - though as Whedon pointed out, it was an uphill battle in the early going.

"It was definitely a challenge early on cause there was certain things we couldn't say, like HYDRA. And so we spent a lot of time laying groundwork and then when we were able to pay all that off, we really felt the reward of being in the Marvel universe and feeling it all be connected."

For more from Whedon and Tancheon - including what they had to say to the question of crossovers with Netflix's forthcoming Marvel series - click on the video above for the full interview.