When most people think back on the child celebrities of their time, they likely think of child movie actors, the well-trained stars of showbiz. For some, these were stars like Mary Kate and Ashley Olson, or Macaulay Carson Culkin from "Home Alone." For others, they were Judy Garland or Shirley Temple.

For kids these days, however, some of the biggest stars are not actors at all but YouTube stars.

And one of the biggest of them all is a 6-year-old named Ryan who plays with toys — mesmerizing millions of children across the globe.

Since he was 3 years old, Ryan's parents have been capturing videos of him opening toys, playing with them and "reviewing" them for videos posted on their YouTube channel,"Ryan ToysReview."

Ryan's last name, and his place of residence are a closely guarded secret, and not without reason.

Ryan has become a multi-millionaire, according to Forbes magazine's just-out list of highest paid YouTube entrepreneurs. He was ranked number eight, having brought in $11 million in revenue between June 1, 2016, and June 1, 2017, before management fees and taxes, of course. He tied with the comedy channel Smosh, created by Anthony Padilla and Ian Hecox.

Children everywhere have become hooked, watching his videos for hours a day, even mimicking him and starting their own YouTube channels. For some of his youngest fans, Ryan is not just some stranger on the internet. He is their friend.

Combined, the world's 10 highest-paid YouTube stars earned $127 million, up 80 percent from last year. According to Forbes, this boost came thanks to ad dollars from a surge in views — including a healthy sum from "Ryan ToysReview." During the 12 months considered by Forbes, "Ryan ToysReview" counted over 8 billion views.

What has grown into a viral phenomenon began with a simple, unremarkable 15-minute video about a Lego Duplo train set. When his family started recording and posting the videos in March 2015, the 3-year-old barely had any views let alone reviews, according to a profile of Ryan in Verge. In his first video, he simply opened a Lego box, set up the blocks, and played with them.

"Ryan was watching a lot of toy review channels — some of his favorites are EvanTubeHD and Hulyan Maya — because they used to make a lot of videos about Thomas The Tank Engine, and Ryan was super into Thomas," his mother, who declined to be named, told TubeFilter last year.

"One day, he asked me, 'How come I'm not on YouTube when all the other kids are?' So we just decided — yeah, we can do that. Then, we took him to the store to get his very first toy — I think it was a Lego train set - and it all started from there."

Soon the boy started playing with not just one toy at a time, but two, and then dozens. About four months in, his channel saw an explosion of traffic, driven primarily by a viral video of Ryan reviewing a hundred toys at once. It is titled "100+ cars toys GIANT EGG SURPRISE OPENING Disney Pixar Lightning McQueen kids video Ryan ToysReview"

"Ryan ToysReview" took off. Views started doubling every month. In January of 2016, he hit 1 million subscribers. A year later, he had more than 5 million. Now, he's at more than 10 million subscribers and over 16 million views.

In June, TubeFilter ranked "Ryan ToysReview" as the most viewed YouTube channel in the U.S. for the 40th week in a row. In September, NBA player Kevin Durant was featured in one of Ryan's videos performing a children's science experiment.

Ryan's popularity makes perfect sense. He's got every small kid's dream job, opening toys and playing with them, day after day. He's smiley, too, totally non-threatening to parents and children alike. No bad words. No preachy banter. He's a miniature Mister Rogers but without the sweater and slippers.

In his most popular video, published April 13, 2016, Ryan's mother films him as he crawls through an inflatable water slide, searching for giant Easter eggs. He cracks open each one to find various toys inside.

"It's Lighting McQueen!" he says excitedly as he opens one to find a toy car from the Disney movie "Cars." And wow, in another there's a character from "Paw Patrol," in another, there's Spiderman.

"I bet there's a bad guy in there," he says, gesturing at one of the uncracked eggs. "Who do you think it is, kids?"

He spends much of the rest of the video tossing the toys down the water slide, playing with them in an inflatable pool.

Ryan's got great timing too. He specializes in the slow reveal, like the opening of those eggs, and in surprise.

Of his 30 most popular videos, more than half include the word "SURPRISE" in all caps in the titles: "GIANT EGG SURPRISE," "HUGE EGGS SURPRISE TOYS CHALLENGE," "BALLOON POP SURPRISE," "SURPRISE TOYS Giant Ball Pit Challenge."

There's no overthinking, no "why is this toy better than another," no analysis, something adults describing "Ryan ToysReview" just can't resist.

The channel was described by Verge as "a mash-up of personal vlog and "unboxing" video, a blend of innocent childhood antics and relentless, often overwhelming consumerism."

"Unboxing" refers to one of today's oddest and most lucrative genres on YouTube. The videos are exactly what they sound like: footage of people opening packages of newly purchased items, the latest Apple devices, Chanel, Louis Vuitton, as the Washington Post's Robin Givhan explained.

Each time someone clicks on one of Ryan's videos, his family makes money. There are ads and links to ads all over the place.

Ryan has real impact.

"If a product gets ten million, twenty millions views, and you see that Ryan loves it, or other kids love it, it has a huge impact at retail," Jim Silver, CEO of the review site Toys, Tots, Pets, and More, told the Verge when Ryan was still 5 years old. "He's really the youngest success that we've seen. Most of the time the kids were in the six-plus range, just because of the vocabulary and the maturity to do a review."

His parents told TubeFilter in September of last year that 99 percent of the channel's videos aren't branded. At the time, the parents said they paid for all of the toys that Ryan reviewed. It's unclear how many toys he currently reviews are sent to him by sponsors, but his video descriptions often include dozens of links to name-brand items. According to his channel's "about" page, the family donates most of the toys to charity after Ryan reviews them.

Many videos include Ryan doing things other than playing with toys. They show him going to get a haircut, playing hide and seek in a hotel, and attending his twin siblings' birthday party.

"We post a new video every day, and we typically film two to three videos at a time two to three times per week," his mom told TubeFilter. "We try not to interfere with Ryan's pre-pre-school schedule, so a majority of the filming takes place during the weekend, and then we'll edit while he's in school."

But even with just a few daily snippets of Ryan's routine, his viewers can virtually insert themselves in his life. And for some young kids, the line is blurred between what's real and what's simply a part of Ryan's videos.

"My 5-year-old EATS THIS STUFF UP!" one mother, Lindsay Weiss, wrote in a blog post titled "Ryan's Toy Review may be the death of me."

"It is literally the only thing he watches on YouTube and the other day I caught him talking back to Ryan telling him he had missed an important feature in the new game 'Don't Wake Daddy.'"

"Honey, you know Ryan can't hear you, right?" Weiss said she told her son.

"He doesn't need to hear me, Mama," her son responded, Weiss wrote. "He just KNOWS."

"I also have Ryan to thank for the THIRTEEN games my kiddo got for his birthday last week," Weiss added. "That's right. My kid got THIRTEEN games for his birthday. All courtesy of seeing Ryan play the games and squeal with delight."

Other parents have left scores of messages on Ryan's YouTube channel, thanking him and his parents, saying their kids sometimes watch his videos for hours a day.

"My son is autistic," one parent wrote. "Your videos are helping him to speak, use his imagination, and properly use toys! He enjoys these videos several times a day and i would just love to say thank you!"

"hey Ryan ToysReview hi there," another parent wrote. "my 3yr old kid Ashaz loves watching your videos. He wants to say hi n says you are his small brother lol. . .we are from India and best wishes from all of us."

"Ryan, my boy loves your toys reviews, every day he watches your videos," one mother posted. "Today he asked me 'mom, when we gonna visit Ryan?', I told him that is not possible because we live in different countries, maybe when you will grow :)"

The greatest testament comes from the children themselves though.

"hello ryan," one of them wrote recently. ". . . i am 5 years old i am in my dad's account how old are you also i love your videos."