If you grew up on mid-2000s comedy, you remember the tiny kid with the giant personality who stole every scene he was in.
Thompson, the pint-sized scene-stealer from "Role Models" and "30 Rock," was everywhere for a stretch — dropping R-rated one-liners as a nine-year-old and holding his own opposite Paul Rudd and Seann William Scott.
Then, like a lot of child stars, he quietly faded from the spotlight.
Now he's 29, and the internet is doing a collective double-take at how different he looks.
Thompson first broke through playing a young Gary Coleman in the 2005 TV movie "Behind the Camera: The Unauthorized Story of 'Diff'rent Strokes." From there he landed the role of Stanley on "That's So Raven," voiced characters on animated series, and became a genuine comedy secret weapon in "Role Models," where his foul-mouthed Ronnie Shields became an instant quotable for a whole generation of teenagers.
He also popped up in "Cloudy with a Chance of Meatballs," "Fred: The Movie," and a memorable arc on "30 Rock." For a while, it seemed like he was on a fast track to becoming one of the rare child performers who makes the jump to adult stardom.
That jump never quite happened the way fans expected.
Thompson stepped back from acting around the early 2010s, and his public appearances became rare.
When photos of him resurfaced recently, comment sections filled up with some version of the same reaction: "That's him?!" Part of the whiplash is that Thompson looks nothing like the round-faced little kid people remember.
He's grown into a full-grown man with a beard, a different build, and a completely different energy.
The gap between the child on screen and the adult in the photos is doing a lot of the heavy lifting in the viral reaction.
It's also a reminder of how brutal the child-star pipeline can be.
Kids who get famous before they hit middle school are often frozen in the public imagination at the age they were most visible.
When they reappear years later, looking like actual adults, it triggers a weird mix of nostalgia and shock that social media can't resist.
Thompson hasn't been completely off the grid.
He's popped up in interviews and on social media over the years, occasionally addressing why he walked away from Hollywood.
In past comments, he's suggested the industry wasn't always a healthy place for a kid, and that stepping back was a choice rather than a failure.
Whether he ever returns to acting full-time is an open question.
What's clear is that the "where are they now" cycle has a new favorite, and this time it's a guy who spent his childhood making grown adults laugh on camera.
There's something oddly satisfying about watching the internet rediscover a performer it never really forgot.
Thompson's moment in the sun was brief, but the movies and shows he was in keep finding new audiences, which means the shock of seeing him grown up will probably happen all over again in a few years.
Final Thoughts
If he ever decides to come back, the nostalgia audience is already waiting.