Harley Bird, 14, Tring, UK

An actor’s life is hard: it’s just one audition after another, and you have to grow a wall-thick skin to deal with all the rejection. For Bird, however, things went a little differently: she was signed to the Alphabet Kidz agency just before her sixth birthday and two weeks later beat hundreds of other young actors to land the lead role in a £1.4bn show.

She is the voice of Peppa Pig, the eponymous piglet who enjoys dressing up and jumping in muddy puddles. Bird, who in real life has two pet pigs (called, of course, Peppa and George), has now voiced Peppa Pig for eight years. Early on, she was too young to read the scripts, but that didn’t stop her winning a Bafta at nine.

The show, while simple in its format of five-minute episodes, has taken the world by storm and is now shown in 180 territories and broadcast in 40 different languages. Not bad for a first role. Were there any clues that this one audition would lead to a starring role in a global franchise? Bird has said she doesn’t understand it herself. “I just auditioned and they said my voice matched. because it is quite husky.”

Mihir Garimella, 16, Pennsylvania

Mihir Garimella won the 2014 Google Computer Science award. Photograph: Courtesy of Mihir Garimella

Some teens might be grossed out by a bowl of bananas starting to rot and attract flies; high school student Garimella came up with a potentially life-saving idea. The “flybot” – a tiny, flying robot that avoids obstacles by mimicking the way a fruit fly avoids threats and moving obstacles – could be used in search-and-rescue missions in dangerous environments, and went on to win the Google Computer Science award in 2014. Garimella has since turned his hand to everything from robotic violin tuners to algorithms that could help doctors diagnose brain tumours.

Shubham Banerjee, 15, California

Shubhan Banerjee, founder of Braigo Labs. Photograph: Bloomberg via Getty Images

When Banerjee turned his Lego bricks into a braille printer for the blind for a school science project, it wasn’t just the famous toy company that was singing the then 12-year-old’s praises. The product, which made computing more affordable for millions of visually impaired people, also caught the attention of Intel, and the award-winning Braigo Labs (an amalgamation of Lego and braille) was born. “He’s solving a real problem, and he wants to go off and disrupt an existing industry,” Edward Ross, director of inventor platforms at Intel, has said. “That’s really what it’s all about.”

Benjamin Kapelushnik: sneaker broker to the stars. Photograph: Complex

What started as a hobby, buying rare trainers and selling them on to classmates, is now a lucrative enterprise. A sneaker broker to the stars (Chris Brown and Drake are fans), Kapelushnik has accumulated 5,000 pairs and is well on his way to making his first million.

Rayouf Alhumedhi, 15, Germany



Rayouf Alhumedhi. emoji designer. Photograph: Courtesy of Rayouf Alhumedhi

While chatting with her friends on social media, this Saudi teen living in Germany realised there was no emoji to represent her, so she designed one. Now she’s campaigning to get it added to phones (it’s currently being considered by the Unicode Consortium). “In this day and age, representation is extremely important,” Alhumedhi said. “People want to be acknowledged. There are so many Muslim women in this world who wear the headscarf. It might seem trivial, but it’s different when you see yourself on the keyboard around the world.”

Willow Smith, 16, California



Willow Smith: youngest artist signed to Jay Z’s record label. Photograph: Broadimage/REX Shutterstock

After making her acting debut at the age of seven alongside her father in I Am Legend, the daughter of Hollywood golden couple Will and Jada Pinkett Smith has forged her own way, becoming the youngest artist signed to Jay Z’s record label, Roc Nation, at 10 – remember Whip My Hair? Since then, she’s swapped the smiley, happy, preteen style for a cooler, pared-back, Instagram-friendly aesthetic. She has starred in a Marc Jacobs ad, and this year Karl Lagerfeld made her his muse, photographing her for Chanel AW16. She and her older brother, Jaden (star of Netflix’s The Get Down, directed by Baz Luhrmann), have been dubbed the “coolest teens on the planet”.

Sasha Obama, 15, Washington DC



Sasha Obama has had a unique global education. Photograph: Getty Images

Barack and Michelle Obama’s youngest has lived her teen years in the White House (she was seven at her father’s inauguration), but stays down to earth: she spent the summer working on the till in a seafood shack (even if secret service agents sat at the tables outside). Her awkward moments have been captured the world over (most recently when Malia, 18, was snapped giving Sasha a sarcastic thumbs up as her little sister spoke to actor Ryan Reynolds at a Canadian state dinner).

More importantly, Sasha has had a unique global education, meeting Malala Yousafzai at the White House, and helping her mother promote women’s education in Liberia and Morocco. In this year’s Thanksgiving message, the outgoing president described his daughters as “funny, smart, humble and extraordinary young women”. All eyes on the next-gen Obamas.

Maddie Ziegler, 14, Pennsylvania



Maddie Ziegler: thrust into the limelight aged eight. Photograph: Bryan Steffy/Getty Images

The pint-sized dancer was thrust into the limelight aged just eight, when she starred on US reality show Dance Moms. But she reached a global audience thanks to Australian singer Sia, who cast her in the video for Elastic Heart. Four videos, several world tours and stage appearances later, Ziegler has become more recognisable wearing her cropped blond Sia wig than sporting her natural hair. She has modelled for Ralph Lauren and become a judge on the junior version of So You Think You Can Dance.

Brooklyn Beckham, 17, London and Los Angeles

Next year Brooklyn Beckham will be bringing out a photography book. Photograph: Richard Isaac/Rex/Shutterstock

Photographing the Burberry campaign, skateboarding through his mother Victoria’s Dover Street store and hooking up with Hollywood ingenue Chloë Grace Moretz; the eldest Beckham kid couldn’t attract more attention if he had followed his father, David, on to the football pitch. Last week, Beckham announced to his 8.8m Instagram followers that next year he will be bringing out What I See, a photography book published by Penguin Random House. If even a small proportion of his social media followers buys the book, he has a bestseller on his hands.

Kiara Nirghin, 16, Johannesburg

This year, as South Africa suffered its worst drought since 1982, a Johannesburg schoolgirl came up with a potential solution. Nirghin found an orange peel mixture had better water-retaining properties than existing “super-absorbent polymers”, which are usually expensive and non-biodegradable. Her invention, which aims to help farmers save both money and crops, is made up of waste products from the juice manufacturing process, including discarded orange and avocado peel; it won Nirghin a $50,000 scholarship at the annual Google Science Fair.

Yara Shahidi, 16, Minnesota



Yara Shahidi: star of acclaimed comedy Black-ish. Photograph: Matt Baron/BEI/Shutterstock

The half-Iranian star of acclaimed comedy Black-ish (a sitcom about an upper-middle-class African American family) is passionate about media diversity: “We are in the middle of a ‘representation renaissance’,” she has said. She is “constantly… in conversation about keeping roles for women and people of colour multifaceted and representative of our true nature”.

Flynn McGarry, 17, New York

Flynn McGarry: has taken up residency in New York’s Kava espresso bar. Photograph: Courtesy of Eureka

Sick of being cooked “kid food” by his parents, McGarry took matters into his own hands with a little bit of help from The French Laundry Cookbook. By 11, he was hosting a supper club in his mum’s kitchen, cooking “progressive American cuisine”; at 15, he was charging $160 a head for his eight-course tasting menu. He has now taken up residency in New York espresso bar Kava, under the name Eureka, where his 16-course feasts are becoming the stuff of legend.

Gavin Grimm, 17, Virginia

Grimm didn’t plan to become the poster boy for a national fight for equal rights for transgender students, but when his school wouldn’t allow him to use the boys’ toilets, a long legal battle ensued. The result, now in the hands of the supreme court, could have implications for young trans people all over the US. “That I have the opportunity to ensure that, hopefully, fewer kids – or anybody – will have to go through this in the future makes me feel good,” Grimm said.

Katie Griffiths, Josie Baldwin, Emily Bowes and Alex Hill, all 16, Stratford-upon-Avon



These Stratford Girls’ grammar school pupils were shocked to discover that young LGBT people are at much higher risk of depression and suicide; two years ago they teamed up to create the I’m Okay app, giving support and information to young people exploring their sexuality and gender. Thousands of people have since downloaded the app from the Google Play store; it won a national Apps for Good award in 2014.

Jeffery Xiong, 16, Texas

The US’s second youngest player to become a chess grandmaster, Xiong stormed on to the scene aged 14 and snatched first place at the 24th Chicago Open. He played his first game at five, when he decided to join a friend who was playing by himself. Xiong carried on until he was the world’s under-20 champion, at just 15.

Krtin Nithiyanandam, 16, Surrey

Krtin Nithiyanandam won the Google Science Fair prize. Photograph: Newsquest

In 2015, Nithiyanandam won the Google Science Fair prize for developing a test to diagnose Alzheimer’s 10 years before any symptoms appear. An antibody is injected that then attaches to proteins present in the earliest stages of the disease; the injection contains fluorescent particles that can be picked up on a brain scan.

“This early diagnosis could help families prepare for the future and ensure that existing drugs are used to better effect,” Nithiyanandam explained. The Surrey schoolboy is now tackling the treatment of triple negative breast cancer, a rare form found in 15-20% of women with breast cancer. It doesn’t respond to drugs, and must be treated with a risky combination of surgery, radiation and chemotherapy. “Most cancers have receptors on their surface that bind to drugs like tamoxifen, but triple negative doesn’t,” Nithiyanandam explained. Working at home and in his school lab, he has found a way to block a protein that prevents those receptors from forming, thus turning this type of breast cancer into one that responds to drugs. “Science isn’t about your age, it’s about ideas,” he told Wired magazine.

Mo’ne Davis: the first African American girl to play in the Little League World Series. Photograph: AP

Formerly a Little League baseball pitcher, Davis was the first African American girl to play in the Little League World Series, and the first female to pitch a winning game. The baseball (and basketball) prodigy was spotted at the age of seven while playing with her older brothers. Since releasing her memoir last year, Mo’ne Davis: Remember My Name, she has designed trainers to raise money for Plan International’s Because I Am A Girl campaign, aimed at helping lift girls in the developing world out of poverty.

Ben Pasternak, 17, Australia

Dubbed “the next Mark Zuckerberg”, Pasternak created the chart-topping app Impossible Rush (a colour-matching game) that was downloaded more than 1.3m times and made him a tech star at just 15. That success allowed him to secure just under $2m in funding from major Silicon Valley investors, move to Manhattan and launch his own startup, Flogg. He had noticed that friends were increasingly selling unwanted items to people they knew through Facebook, rather than to strangers on Gumtree or eBay. Yet Facebook “wasn’t really doing anything to look after their user experience”. So he created an app that allows users to buy and sell items through their Facebook connections with a swipe left or right; the Sydney Morning Herald described Flogg as “the love child of Tinder and eBay”.

Lewys Ball, 17, London

Lewys Ball started his own YouTube channel. Photograph: Courtesy of Lewys Ball

Ball was 14 when he became interested in beauty, but could only find makeup tutorial videos aimed at girls; finding what he wanted in Boots was an ordeal. “I was so embarrassed, I didn’t even look at shades and just picked the first products I had seen YouTubers talk about,” he said. So Ball decided to start his own YouTube channel, Looking For Lewys, with tutorials aimed primarily at men. By the time he was 16, he had had over 1.2m views; he now has more than 115,000 subscribers. As well as makeup and fashion tips, Ball shares his favourite music, DIY projects and even anecdotes, in between revising for his A-levels.

Male beauty is having a major moment, and brands are waking up to it. Ball recently signed to Gleam Futures, the talent agency with clients such as YouTube megastars Jim Chapman and Zoella; in the US, male beauty blogger James Charles was named CoverGirl’s first CoverBoy in October. “I think brands have realised that makeup isn’t just for girls,” Ball has said. “It’s for everyone.”

Karamoko Dembele, 13, London

Karamoko Dembele played for Celtic’s under-20s aged 13. Photograph: Getty Images

Dembele has had coaches fighting over him for most of his life. (It has been reported that the football prodigy could do 100 keepie-uppies at the age of five.) London-born, he is eligible to play for Scotland, England and Ivory Coast. In October, aged just 13, he made his debut for Celtic’s under-20 side; he has played for Scotland’s youth team this year, but has since been snatched up by the England under-16s.

Helena Coggan, 17, London

Helena Coggan’s first novel was published when she was 15. Photograph: Pal Hansen

Coggan always wanted to write a novel, and at 13 sat down to have a go on her dad’s laptop. That turned into The Catalyst, a thrilling, magical novel that was published to acclaim when she was just 15. A follow-up, The Reaction, was published this year; she is now working on a third novel while promoting her first around the world.

Ashima Shiraishi, 15, New York



Ashima Shiraishi started rock climbing aged six. Photograph: Visual Impact

Shiraishi started rock climbing in Central Park, aged six. She is now one of the strongest, youngest climbers of all time. Earlier this year, on a spring break to Japan a week before her 15th birthday, she was the first woman and youngest person ever to climb a V15 “boulder problem” (the V scale system begins at V0, a ladder, and goes up to V16).

Amandla Stenberg, 17, Los Angeles



Amandla Stenberg has appeared in feature films since 2010. Photograph: Getty Images

Actor Stenberg, whose first name means “power” in Zulu, is outspoken on racial and gender politics. She has an African American mother, a Danish father, and identifies as non-binary, saying “the concept of gender is not really real”. In 2015, she was named “one of the most incendiary voices of her generation” by Dazed magazine, and feminist of the year by the Ms Foundation for Women.

Though Stenberg had been performing music since childhood, and appeared in feature films since 2010 (including a memorable performance as Rue in The Hunger Games), more recently she has been making waves on social media. She was just 16 when she posted a school project video, Don’t Cash Crop My Cornrows, that promptly went viral. In it, she asked, “What would America be like if we loved black people as much as we love black culture?” Beyoncé invited her to appear on her visual album Lemonade, which was filmed in secret last year. “I just got this phone call,” Stenberg recalled. “It was like, ‘Go to New Orleans; Beyoncé wants you there.’” When Beyoncé met Stenberg, she said, “I just wanted to tell you, I want Blue Ivy [her daughter] to be just like you.” High praise indeed.

Eleanor Green, 13, Stockport

Eleanor Green: dubbed the new Beth Tweddle. Photograph: Andy Lambert/Tameside Advertiser

Dubbed the new Beth Tweddle, this schoolgirl from Stockport landed a spot on the England gymnastics squad this year. Green’s mother works as a lollipop and dinner lady, while her daughter trains for 20 hours a week over six days. She is supported by several trusts and charities, allowing her to prepare for the English and junior British championships next spring.

Hasan Abbas, 16, Mohammed Shakil Ahmed, 15, Itesham Hussain, 14, Luay Ali, 15, and Shayaan Khan, 15, Luton



Team weKonnekt have won several awards. Photograph: Courtesty of Denbigh High School

To help the UK’s 200,000 young carers, these five pupils from Denbigh High in Luton created weKonnekt, an app featuring an online forum, stories from other carers, as well as practical functions such as double-tap access to emergency services and a directory of local services. They have won several awards, and this year presented the app at Wembley Arena to an audience of 12,000 young entrepreneurs. They’re now hoping to launch an iOS version of the app.