Unmasking the 17th Houseguest: Who’s About to Shake Up Big Brother 27?

With the official release of the first 16 all new house guests, the real drama in Big Brother 27 isn’t just who walks through Hotel Mystère’s doors—it’s who will walk through them. CBS teased a 17th, “epic” and “very polarizing” mystery houseguest entering during premiere week—a reveal that already has fans buzzing.

So who could it be?

First theory: a returning legend.
Few things deliver instant intrigue like a fan-favorite—or fan-frightening—veteran returning to the game. With the clue-filled set (think hidden passageways, secret accomplices) it’s easy to imagine a former season champion like Derrick Levasseur (a detective-themed mystery fit, right?) making a dramatic re-entry. Reddit sleuths even noted a clue from a clock reading “1:16”—coded as “won 16”—sparking Derrick speculation. Or perhaps, Rachel Reilly is coming back as the below X user theorizes..

CONFIRMED: RACHEL REILLY IS THE MYSTERY HOUSEGUEST #BB27
how do i know?
the map can symbolize Amazing Race, but if we look closer, we see the coorindates…
20°31"S 24°
and what seasons did Rachel Reilly compete on the Amazing Race? 20, 24, and 31. pic.twitter.com/sBoc43V9mI

— sam ? (@saminlisbon) July 8, 2025

Second theory: a CBS reality crossover.
Remember when Survivor star Cirie Fields crashed a finale? CBS loves cross-franchise shake-ups. Julie Chen Moonves hinted the mystery guest “spark[s] strong reactions both ways.” Someone like Parvati Shallow (Survivor Micronesia winner) would light up both fandoms—thrilling some, annoying others.

Third theory: a wild card outsider.
What if it’s not reality-famous at all, but someone polarizing? Imagine a political commentator or influencer—someone with built-in drama and divided opinion. Julie’s teaser fits this angle too: “unexpected,” “polarizing”—perfect for stirring up both cheers and boos.

Fourth Theory: A Controversial Past Contestant Looking for Redemption
CBS has a history of leaning into controversy when it serves the drama—and nothing gets fans talking like a polarizing return. What if the 17th houseguest is a previously disgraced player? Think someone like Aaryn Gries (BB15) or Jackson Michie (BB21)—both highly divisive figures from seasons that sparked intense public backlash. The idea of a redemption arc—or a second chance to answer for past behavior—would draw massive attention (and debate). Julie’s comment that this houseguest “sparks strong reactions both ways” lines up perfectly. It would be risky, but Big Brother has never shied away from controversy when it comes to ratings.

Fifth Theory: A Social Media Star or Influencer with No BB Ties
With TikTok and Instagram creators increasingly crossing over into mainstream media, CBS might be shaking up the traditional cast formula. A well-known influencer with millions of followers—but zero Big Brother knowledge—would be a bold experiment. Imagine the drama of throwing a Gen Z internet celeb into a house full of super-fans and strategy sharks. The audience might love to hate them—or hate how much they love them. Either way, they’d be talked about. The “polarizing” label fits here too: adored by followers, questioned by diehard BB fans.

So what’s more likely?
My bet: a past Big Brother champ—like Derrick—stepping back into the spotlight. The elaborate mystery theme, detective vibes, and hints about clue-filled surprises feel tailor-made for someone who knows the game inside out. Plus, a returning player keeps fans invested.

Whether it’s a disgraced alum, a viral sensation, or someone else entirely, one thing’s clear: CBS wants this mystery player to set the tone. And they absolutely will. No matter who it is, we’ll find out during the dual episode premiere starting July 10. Until then, my popcorn’s ready—and I’ve got my guess locked in. Who’s yours?

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