If you’ve spent any time binging Criminal Minds, you know that the show isn’t just about the "unsubs" or the gruesome crime scenes. It’s about the BAU family. And in the middle of all that profiling and darkness, there was always Henry LaMontagne. He’s the tow-headed kid who grew up right before our eyes, usually dressed as a mini version of Spencer Reid for Halloween. But here is the thing that usually trips people up: the kid playing Henry isn't just some random child actor found at an open casting call in Burbank.
The answer to who plays Henry on Criminal Minds is actually a bit of a "meta" moment for the series. Henry LaMontagne is played by Mekhai Andersen.
If that last name sounds familiar, it’s because it is. Mekhai is the real-life son of A.J. Cook, the actress who portrays Jennifer "JJ" Jareau.
Why the Casting of Mekhai Andersen Actually Mattered
Most TV shows use "twins" to play young children to get around strict child labor laws. Think Full House or Friends. But Criminal Minds took a different path. When A.J. Cook became pregnant in real life during the show's fourth season, the writers didn't hide it behind giant handbags or strategically placed laundry baskets. They wrote the pregnancy into JJ’s storyline.
When it came time for JJ to have her son, the production brought in Mekhai.
He first appeared in the episode "100," which, if we’re being honest, is one of the most traumatizing hours of television ever produced (RIP Haley Hotchner). Seeing a real-life mother-son bond on screen added a layer of vulnerability to JJ that stayed with the character for fifteen seasons. You can’t fake that kind of chemistry. When JJ looks at Henry with that specific mix of terror and love—the kind that comes from being a federal agent who knows exactly how dangerous the world is—that’s A.J. Cook looking at her actual child.
It’s rare. Honestly, it's almost unheard of for a child to stay in the same role for over a decade in a procedural drama. Mekhai started as a literal infant and eventually grew into a teenager on the show.
The "Uncle Reid" Factor
We have to talk about Matthew Gray Gubler.
In the show, Spencer Reid is Henry’s godfather. Because Mekhai grew up on set, the bond between him and Gubler wasn't just scripted. There are countless behind-the-scenes stories of Gubler entertaining Mekhai between takes. This led to one of the most iconic character beats in the show: Henry LaMontagne wanting to be Spencer Reid for Halloween.
That wasn't just a cute writer's room idea. It felt earned because the audience had watched that relationship evolve since 2009. If you look closely at the episodes where Henry appears, especially in the later seasons of the original run, the height difference between him and A.J. Cook starts to get hilarious. He went from a baby in her arms to nearly towering over her.
It’s a Full Family Affair
Believe it or not, the family ties don't stop with Mekhai.
A.J. Cook has another son, Phoenix Sky Andersen. And guess what? When the show needed a second son for JJ and Will (Michael LaMontagne), they didn't go to an agency. They hired Phoenix. He plays Michael, Henry’s younger brother.
So, when you see the LaMontagne family sitting around their kitchen table in Virginia, you are looking at a real family. Well, except for Josh Stewart, who plays the husband/father, Will. He’s the only one not related by blood, though after years of filming, he’s basically an honorary Andersen at this point.
Josh Stewart’s chemistry with the kids is also worth noting. He brings this grounded, Cajun-detective energy that balances out the intense BAU drama. Having real siblings play siblings on screen is a "cheat code" for directors. You don't have to teach two child actors how to bicker or share a toy; they’ve been doing it in the trailer for three hours already.
The Evolution in Criminal Minds: Evolution
When the show was revived as Criminal Minds: Evolution on Paramount+, fans were curious if the "kids" would come back.
By this point, Mekhai Andersen was no longer a little boy. He was a teenager with a deep voice and a completely different vibe. The writers leaned into this. In the revival, Henry isn't just a background prop used to show that JJ has a life outside the office. He becomes a central part of the tension.
He’s a teenager now. He’s observant. He’s the son of two law enforcement officers. He starts noticing things—like his mother’s exhaustion and the secrets she keeps. The casting of Mekhai allowed the show to explore a very specific type of "BAU brat" storyline. What happens when a kid is raised by people who hunt serial killers?
Why People Keep Searching for Him
People keep asking who plays Henry on Criminal Minds because, frankly, he looks so much like A.J. Cook that it’s jarring. Usually, TV kids look nothing like their parents, and we just collectively agree to ignore it. But with Mekhai, the resemblance is undeniable. The eyes, the hair—it’s a carbon copy.
There’s also the nostalgia factor. For fans who have been watching since 2005, seeing Henry is a marker of time. We measure the age of the show by how old that kid is.
What’s Next for Mekhai Andersen?
Unlike many child stars, Mekhai hasn't flooded his resume with dozens of other roles. His filmography is almost exclusively Criminal Minds. This suggests a few things. One, he’s likely living a relatively normal life outside of the occasional TV shoot. Two, his involvement is likely a way to spend time with his mom at "the office."
A.J. Cook has often spoken in interviews about how much she treasures having her boys on set. It turns a grueling filming schedule into a family activity.
For those looking to follow his career, you won't find him in the latest Marvel movie or a Nickelodeon sitcom. He seems content being the BAU’s favorite son. However, as Evolution continues to get renewed, his role is shifting from "cameo kid" to "supporting actor." He’s getting more dialogue and more complex emotional beats.
A Quick Reality Check on the Cast
If you're digging into the LaMontagne family tree, here’s the breakdown you need to keep the facts straight:
- JJ Jareau: Played by A.J. Cook.
- Will LaMontagne Jr.: Played by Josh Stewart (First appeared in Season 2).
- Henry LaMontagne: Played by Mekhai Andersen (A.J. Cook’s eldest son).
- Michael LaMontagne: Played by Phoenix Andersen (A.J. Cook’s younger son).
It's a rare setup. Most procedural shows, like Law & Order or NCIS, tend to swap out child actors as they age or if they become "difficult" to work with. The fact that the Criminal Minds team kept it in the family for nearly two decades says a lot about the culture on that set. It’s also probably why the show has such a die-hard fanbase. It feels real because, in some ways, it is.
When you're watching the later seasons and you see Henry looking a bit moody or Michael running around the house, remember that those aren't just child actors hitting marks. They are kids who literally grew up on those soundstages. They’ve seen the fake blood, the prosthetics, and the "jet" more times than most people see their own living rooms.
To see the progression for yourself, go back and watch Season 4, Episode 18 ("Omnivore"). That’s where the Henry journey really kicks off. Then jump to Criminal Minds: Evolution. The transformation is wild. It’s a rare piece of TV history where the "growing up" isn't a montage—it’s documented in real-time over 15 years.
The next time you’re watching a JJ-centric episode and Henry pops up on the screen, take a close look at the background photos in their house. Many of those aren't props created by the art department; they are actual family photos from the Andersen household. If you want to keep up with the latest on the Criminal Minds cast, the best place isn't actually the tabloids. It’s A.J. Cook’s social media. She occasionally shares glimpses of the boys behind the scenes, and it’s clear that while Mekhai plays Henry on screen, he’s just a regular kid who happens to have a very cool, very creepy family business.
Check out the most recent season of Evolution on Paramount+ to see how Mekhai’s role has expanded. It’s a much grittier take on the character than we saw in the early 2010s, reflecting the darker tone of the revival. And if you're a trivia buff, keep an eye on the credits—you'll see the Andersen name pop up more than once.
Actionable Insight: If you're interested in child acting or the mechanics of long-running TV shows, Mekhai Andersen's career is a perfect case study in "legacy casting." It shows how production can maintain continuity and emotional weight by utilizing real-life relationships. For fans, it's worth re-watching JJ-heavy episodes like "200" or "Tall Man" to see how the writers used Henry's presence to raise the stakes for JJ’s character. Knowing the real-life connection makes those high-tension scenes where the family is in danger feel much more visceral.