Grande is the 31-year-old half-brother of pop sensation Ariana Grande. He's currently a contestant on Season 16 of Big Brother, but has an already-established fan base of "Frankiesteins" thanks to his YouTube channel, which boasts more than 220,000 subscribers and features original videos under weekly themes like "FrankieFriday" and "ToplessTuesday" And there's no sibling rivalry here — Ariana is a fixture in Frankie's videos and on his Twitter feed.

On 17-year-old Teala Dunn's YouTube channel, her 350,000-plus subscribers are treated to videos highlighting the New Jersey native's monthly favorite things, her routines and fashion choices based on the season, and Q&A sessions covering such topics as crushes, kissing and The Fault in Our Stars. When she's not making YouTube videos, Dunn is an aspiring actress who's had roles on Dog with a Blog and Enlisted, as well as a starring role as Lindsey on TBS' Are We There Yet?

Billed as "The 6-Year-Old Comedian," Zay Zay Fredericks and his brother Jojo make their own YouTube videos, which are published every Saturday on AwesomenessTV. The clips feature the boys dancing, ranting and offering sage life advice. Between their two official channels, the siblings have more than 60,000 followers.

Jenn McAllister may not be a household name yet, but she's one of YouTube's hottest young celebrities, with more than a million subscribers. The self-made star, who just turned 18, posts videos covering topics like "Funniest School Stories," "Types of People Who Annoy Me," and "How to Be Successful on the Internet." She would know!

Hunter March is the host of AwesomenessTV's Daily Report, as well as his own weekly vlogs — which include clips on family vacations, sketches like "S--- Valley Girls Say," and the semi-regular #AskHunter and #DearHunter series, in which March candidly responds to questions from his 83,000-plus subscribers.

Though she started out uploading videos of herself performing at church recitals and school talent shows, Johnson cultivated enough of a fan base to be one of the biggest young stars on YouTube in 2014, according to Adweek. The 17-year-old Hawaii native, who boasts more than 1 million subscribers, is starring in Nickelodeon's Terry the Tomboy movie, a spin-off of the AwesomenessTV comedy sketch. She's also a regular in the Fine Brothers' "Kids React" and "Teens React" series, and the numerous cover song videos she's posted include some dead-on impressions of Miley Cyrus.

Cimorelli is a band comprised of six sisters from California — Christina, Katherine, Lisa, Amy, Lauren and Dani Cimorelli, ranging in age from 14 to 24 — who parlayed their YouTube fame into a record deal with Universal Music. Though they started out posting mostly a cappella covers beginning in 2007, the girls eventually began treating their fans (nearly 3 million subscribers to date) to original songs. As of mid-2014, they've released three EPs and are now starring in their own scripted comedy web series, Summer with Cimorelli.

You may not know Felix Arvid Ulf Kjellberg by his name (or his online alias, PewDiePie), but chance are you've seen one of his videos. The 24-year-old Swedish Internet prodigy has nearly 30 million subscribers on his YouTube channel, making him the site's top-subscribed channel in 2013. There, he posts bizarre, often hilarious, animated videos with titles like "How to become a pigeon and escape life forever" and "Useful Swedish words that you should know," and also runs charity fundraising drives. But he's most known for filming his reactions to action and horror video games as he plays them.

"Stampy" (a.k.a. Mr. Stampy Cat) is a one-stop shop for gamers looking to get tips and commentary. The account, to which more than 3 million YouTube users subscribe, uploads at least one Minecraft video per day, in addition to videos on various other titles like Mario Kart, Sky Den and The Forgotten Vale.

"Miranda Sings" is a character created by comedienne Colleen Ballinger, who describes her egotistical alter ego as a "5 threat" (singing/dancing/acting/modeling/magician) who hopes to break into show business by uploading (horrendous) cover versions of pop songs twice weekly. Ironically, the character — who's gained more than 1.6 million subscribers — was created to satirize the very type of YouTube fame she's managed to cultivate. In addition to her music videos, Miranda also posts helpful tutorials like "How to Cuddle" and "How to Ride a Child."

Who would win in a (rap) battle between Steve Jobs and Bill Gates? Stephen King and Edgar Allan Poe? Or what about Moses and Santa Claus? Find out by watching Epic Rap Battles, which pits historical (and fictional) characters against each other to determine who can spit out the better rhymes.

James Wilson, better known as UberHaxorNova on YouTube, has cultivated a following by uploading videos of himself playing inappropriate gags on people, as well as offering loud commentary on video games. With about 2.5 million subscribers, Wilson is a member of the online group the Creatures, and focuses on game titles like Minecraft and Call of Duty.

Though he focuses mostly on video games, 22-year-old Jordan Maron (aka Captain Sparklez) also posts music videos and other animation for his 1.5 million subscribers. His channel was the fifth solo-gaming channel to reach 1 billion views, thanks in part to his "Minecraft Style" video, a parody of Psy's "Gangnam Style" that went viral in 2012.

Jenna Mourey, better known by her online alias Jenna Marbles, is a 27-year-old comedian who runs the top female-operated channel on YouTube, with 13.5 million subscribers. Some of her more popular videos include the "What Girls and Guys Do" series ("Things Guys Lie About" vs. "Things Girls Lie About," etc.), as well as "Drunk Makeup Tutorial" and "Jenna's Drunk Art School."

Actor/comedian Toby Turner actually runs three YouTube channels — one for personal videos, one for "Lazy Vlog" videos and one focusing on games. The 6.7 million users who subscribe to TobyGames watch Turner play titles like Amnesia and Minecraft, while his other channels include video game-themed original songs (i.e. "Mine the Diamond"), as well as literal video game trailers.

The Oklahoma City native started his "Equals Three" series while studying at Columbia University, Johnson provided commentary on viral videos, with featured celebrity guests including Robin Williams, Jason Biggs, Margaret Cho and Sarah Silverman. He also launched the animated music video YouTube channel "YourFavoriteMartian" in 2011 and released the web series Riley Rewind in 2013. That year, he also signed a development deal to produce a sitcom for FX.

The comedy duo of 26-year-olds Ian Hecox and Anthony Padilla, collectively known as Smosh, is a virtual dumping ground for comedy, animated, and video game content and more. (They've also launched the Spanish spin-off channel ElSmosh.) The more popular videos among their 18.2 million subscribers include the annual Food Battle series, the If ____ Was Real series and video game-themed music videos.