The show (which also features a young Jessica Alba), replaced Clarissa Explains It All in Nickelodeon's SNICK Saturday night programming block, and ran for four seasons, before Oleynik, who described herself as "burnt out" by the show's success, walked away from a fifth season offer, a feature film and – in her words – "a ton of money."
But let's not dwell on what might have been. Let's instead, dig up some fun facts about the show that let so many kids of the 1990s imagine a world full of special powers, secrets and amazing headwear.
Oleynik was frequently approached by kids who asked her to "morph" for them.
Rather than spoil the illusion for viewers too young to understand the show's special effects, Oleynik's stock response was to look around quickly, then say, "Not here – everybody would see!"
The show's creator's childhood inspired the show.
Thomas W. Lynch, who created the show, was the son of a nuclear physicist. Lynch's dad said his father frequently worked with radioactive material – in the family garage. "It cracked me up," he told the Huffington Post in 2012. "What if I ate it? What would happen to me?"
About 600 girls auditioned for the role of Alex.
"Larisa came in and I remember looking around the room and saying, 'That's it. That's the one. I can write for her,' " Lynch said. "[The network] said, 'OK, send a tape,' and I said, 'No, no, no. That's the one. She's it.' "
Oleynik kept a few of Alex's hats.
"I still have so many of those hats," Oleynik told HuffPo. But Lynch says Alex's iconic baseball hat (which he kept in his possession after the show wrapped) was contributed by the show's costume designer, Laura Slakey. "The most iconic thing in the show, I had nothing to do with."
The show's cliffhanger isn't a cliffhanger.
The show's season four cliffhanger, in which Alex's father gives her a vial with a chemical that would "cure" her of her powers, ended on an ambiguous note, with Alex holding the vial and smiling at the camera. But Lynch says there's no ambiguity in his mind as to whether Alex took the cure: "She never did."
Lynch and Oleynik differ on where Alex would be now.
Lynch says that today, Alex is the mother of two teens, using her powers to help raise her kids and deal with her husband. Oleynik has a different idea: "Somehow I think she's a teacher. Is that weird? I feel like she's a cool teacher, who's still using her powers on the sly every once in a while to help out her favorite students."
There's no Alex Mack reunion planned.
"I would do a movie as a remake to launch a [new] series," Lynch says. "I think with all the girl power stuff going on ... I see the stuff on The CW. I think the way to do Alex Mack is to do it as a feature that goes into a series. I think there's a way to do it that will still be cool and interesting. I did always want to see what she'd be like in college. Kind of like Felicity meets Alex Mack.