Being Marvel witch Agatha Harkness has put such a spell on Kathryn Hahn, she didn’t think twice about buying her Lego figure on Amazon.

“She has her own (dress) train; she's holding a Darkhold. I really feel like I've made it,” says the actress and star of the new Disney+ series “Agatha All Along.” “The sad thing is I bought it and put it together myself, and I loved every second of it. Still needed to look at the instructions.”

Hahn, 51, has played many best friends and supporting roles in movies and TV over the years, but now is enjoying her latest lead-actress era with the 2023 Hulu dramedy “Tiny Beautiful Things” and now “Agatha.” She captured superhero fans’ hearts and minds – and garnered a kicky theme song – as the chief antagonist of the 2021 series “WandaVision”: Agatha posed as the nosy neighbor of Wanda Maximoff (Elizabeth Olsen) and Vision (Paul Bettany) to use the Darkhold, a magical tome, to steal Wanda’s considerable powers as the Scarlet Witch.

Join our Watch Party!Sign up to receive USA TODAY's movie and TV recommendations right in your inbox

Agatha was defeated and her magical powers were taken by Wanda. That’s where we reunite with “Agatha” (first two episodes streaming at 9 p.m. ET/6 PT tonight, then weekly on Wednesdays). She’s stuck in a “True Detective”-style TV show world until old frenemy Rio Vidal (Aubrey Plaza) snaps her out of it. To get her groove back, Agatha takes on the trials of the mythical Witches’ Road with a makeshift coven that includes Teen (Joe Locke), Agatha’s young new friend, who's unable to say his real name because of a curse. 

Need a break? Play the USA TODAY Daily Crossword Puzzle.

“Through this personal journey, we open the world of the MCU to witches, which is so awesome, and also we really open up the message of finding one's own power,” Hahn says. “How do we evolve? How do we look at growing older? Can we see that it's the most powerful chapters the older we get? That the wisdom that we have gained becomes an asset and not a liability is really charged and exciting.”

But Agatha hasn’t lost any of her deceptive ways. In “WandaVision,” she “delighted in this long game of cat and mouse,” Hahn says. “You never really knew intentionally what she wanted from Wanda. Besides the power, was it friendship? Was it a lover?” Her “shape-shifting” continues in the new show, though it’s more subtle. “She gets to perform, gathering this coven of depressing witches,” the actress adds with a laugh. “She's trying to pull one over on them every time she's trying to gain sympathy. She's the same Agatha. She's just using those tactics in different ways.”

The fact that Agatha earned her own spinoff was delightful news to Hahn: “I just thought I would ride this ride and be like, ‘See ya,’” she says of her “WandaVision” stint. But her enchanting take on a mid-tier Marvel Comics character was a hit with fans and Marvel executives. Getting the call about the show was “like a fever dream,” she reports, recalling bursting into tears when one of the “WandaVision” production assistants wished her well on the first day of filming “Agatha.”

“This is nothing I would've thought for myself in the future, in my career, any of this. And for it to be a witch is beyond my wildest dreams.”

The actress loved diving headfirst into the comic-book history of Agatha, a centuries-old personality who first appeared in a 1970 issue of “Fantastic Four.” Over the decades, the character showed up on the page as a mentor or a nanny, protector or mother figure. Sometimes she’s an old woman, other times not so much. “Clearly there was a moment in time where every Marvel heroine had to be in a bodysuit with big cleavage. I was like, ‘Can we bring that Agatha back?!’” Hahn jokes.

Her Agatha ended up being “a crockpot of a lot of different experiences,” she says. There was a little bit of the Tin Man she played in her Cleveland high school production of “The Wizard of Oz” – “With a little funnel on my head, I felt like that was kind of preparing me” – and also a major infusion of her love of dark comedy. “That sense of humor has a lot of freedom in it and a little bit of rage behind it and those are some qualities that I feel like maybe as women we haven’t been able to express as loudly and taking up as much space,” Hahn says.

She also points to her recent string of lead roles that dug into moral gray areas, from TV shows “I Love Dick” and “Mrs. Fletcher" to films like “Private Life” and “Afternoon Delight.” “Those women directors (and) writers really wanted my whole authentic self.

“I know this sounds like a cliché, but I really love acting. I'm an old workhorse,” she adds. “It could be lead, it could be supporting, it could be what have you. I don't have a huge agenda, (but) I have loved playing Agatha Harkness. So this really was a treat.”

Contributing: Gary Levin