Larisa Oleynik as Alex Mack
After Alex Mack ended in 1998, Oleynik starred in the now-'90s classic 10 Things I Hate About You, recurred on 3rd Rock From The Sun, guest-starred on a handful of Pretty Little Liars episodes, and was a regular on Hawaii Five-0 until 2014. She can currently be seen on the final season of Mad Men as Cynthia Baxter.
Meredith Bishop as Annie Mack
Darris Love as Ray
Love went from one beloved '90s show to another, playing Jamal on Sister, Sister's final season. He's also guest starred on a ton of shows — from Buffy the Vampire Slayer to CSI and Shameless — and starred in a few TV and indie movies.
Dorian Lopinto as Barbara Mack
Since playing Alex's mom, Lopinto's guest-starred on dramas Cold Case and Strong Medicine, and done a few indie films. Her latest project is the web series Flip and Glib... And the Theory of Everything.
Michael Blakley as George Mack
Judging by his IMDb page, Blakley took a long break from acting after wrapping up the Nickelodeon series — he only has two credits since the show: the 1999 TV movie The Sky's On Fire and a 2011 guest spot on Pretty Little Liars (above).
Natanya Ross as Robyn Russo
Ross was everywhere in the '90s, with guest spots on shows Boy Meets World, ER, and Baywatch, and a co-starring role in The Baby-Sitter's Club with Alex Mack co-star Larisa Oleynik. She seemingly left "the biz" in 2000, after a guest spot on Boston Public, but is pretty active on Instagram today.
Alexis Fields as Nicole Wilson
Fields (sister of Facts of Life and Living Single star Kim Fields) has worked a lot since Alex Mack. She also joined the cast of Sister, Sister (as Diavian), played Sharla on Kenan & Kel, and was Alicia on Moesha. She's currently starring in the WorldStarHipHop original series All That Matters.
Benjamin Kimball Smith as Louis Driscoll
Smith was another child actor who was everywhere in the '90s, with TV guest spots on shows like Roseanne and The Nanny, and a part in Jerry Maguire. After Alex Mack, Smith took a long hiatus from acting — he didn't start working again until 2010, when he starred in the web series The Road to Margaritaville (above).
Hilary Salvatore as Kelly Phillips
After playing Alex's middle school rival, Salvatore went on to guest star on a ton of shows — Dharma & Greg, Beverly Hills, 90210, Gilmore Girls, The West Wing, and Sean Saves The World (above) to name a few. Salvatore — who now goes by Hilary Angelo — also had parts in American Pie, Bring It On, and Charlie Wilson's War.
John Marzilli as Vince Carter
Since his time as Paradise Valley Chemical's on-call henchman, Marzilli has made the rounds on a bunch of crime series — he's appeared on NYPD Blue, Cold Case, Without a Trace, and Criminal Minds (above).
John Nielsen as Dave Watt
Nielsen's kept busy since his days as Paradise Valley Chemical's dimwitted driver — he's had guest spots on shows including NYPD Blue, 24, Third Watch, Ghost Whisperer, Criminal Minds, Rizzoli & Isles, and most recently, The Blacklist (above).
Will Estes as Hunter Reeves
Estes joined the cast of Alex Mack for the series' final episodes as Alex's love interest/boyfriend. He went on to have roles on 7th Heaven and American Dreams, and can currently be seen as Jamie Reagan on CBS's Blue Bloods.
Jessica Alba as Jessica
Yes, Jessica Alba got her start on Alex Mack as Atron Junior High's original mean girl. She did just three episodes before the show introduced Kelly, and that totally killed her career. Just kidding — Alba, of course, went on to become a major movie star and mommy mogul.