CBS' FBI May Have Just Debuted The Season 8 Big Bad, And The Timing Would Be Perfect For An FBI: International Or Most Wanted Guest Star

Warning: spoilers are ahead for Episode 4 of FBI Season 8, called "Manifest" and available streaming next day with a Paramount+ subscription.

FBI is generally one of the most procedural shows in primetime, but the CBS drama may have just introduced an ongoing big bad in the 2025 TV schedule. He has all the hallmarks of a great villain: smart, scary, ruthless, and a close call with killing one of the main characters. It's also easy to believe that the team might not be able to catch him right away. He sets up an interesting storyline for FBI, but a fugitive with global reach just makes me think of FBI: Most Wanted, FBI: International, and all the characters who could be great guest stars despite the spinoffs getting cancelled.

The new bad guy is a killer by the name of Oslo, who had Senator Hirsh as a target before she could vote on an amendment that would help veterans. Despite the best efforts of Maggie and OA on what was supposed to be the flight safely transporting her to D.C. for the vote, Hirsh was dosed by a neurotoxin that killed her in less than an hour. Before they could figure out who was responsible, OA was then exposed.

Meanwhile, the agents back at 26 Fed made some troubling discoveries. The neurotoxin was a match for cases in Norway, Brussels, and Cairo, all of which linked to an unknown suspect associated with high-profile murders that included royals and government leaders. The international assassin was wanted in more than a dozen countries, and known as "Oslo" by MI5.

Through some teamwork, Maggie and Co. figured out that the culprit was somebody who was wearing an elaborate disguise, and Maggie applied enough pressure to get him to give up the antidote in time to save OA.

And Maggie was in no mood to deal with Oslo afterwards. Despite his offer for dirty little secrets on powerful players on the international stage, she was stuck on him nearly getting OA killed. (Seriously, I love Maggie and OA's partnership.) She wasn't buying what he was selling when he told her that the identity of his clients "is of great interest to people here, in Washington, and the Hague."

Unfortunately for Maggie, Isobel and higher-ups were inclined to agree with Oslo about the value of the names being worth a deal. The plan was for Scola and Eva, played by new series regular Juliana Aidén Martinez in the wake of a major death, to escort Oslo to safety to start dropping names, although Eva was worried about an attack from some of those people who would kill to keep Oslo quiet.

Rightfully worried, as it turned out! The convoy was attacked, with bullets flying, bodies dropping, and Oslo somehow making an escape. He's in the wind, with a résumé of crimes that prove he knows how to disappear before the time is right to strike. Maggie dropped by the hospital to visit OA, but she had that bad news to deliver along with a pint of ice cream. After she dropped the bombshell of Oslo's escape, they had this exchange:

• Maggie: "The good news is now every intelligence agency in the world has his photo."
• OA: "Then it's our turn to honor [Senator Hirsch]."

In light of that ending, wouldn't the ongoing case of Oslo's escape be a great opening for somebody from the cast of FBI: International and/or FBI: Most Wanted to at least make a cameo? As viewers likely remember from watching the finales back in the spring, International didn't really end on any kind of final note, so there's no reason why any of those agents couldn't pop up.

Of the Most Wanted team, Remy retired at the end of the series finale, but the rest of the crew was still with the Bureau. Heck, Nina is still presumably in a happy relationship with Scola off-screen, so it wouldn't even be a stretch for Shantel VanSanten to show up. Back in the day when all three shows were airing, it wasn't uncommon for a character from one show to contribute via a Zoom or phone call.

Whether a full guest appearance or just a cameo, I feel like Oslo as a big bad could be a great way for the 26 Fed crew to call on the expertise from some other departments of the Bureau. I'm not terribly optimistic that it'll happen, and I love that Oslo was set up as a potential personal nemesis for OA in particular, so we'll just have to wait and see what comes next.

New episodes of FBI air on Mondays at 9 p.m. ET on CBS, ahead of Watson Season 2. You can also revisit earlier seasons of the hit drama on Paramount+, while FBI: International and FBI: Most Wanted are both available with a Peacock subscription.