Hello World is a live show in which the UK's biggest YouTube stars perform for and meet with their fans on 28 and 29 October.
Zoe Sugg started her blog and YouTube channel in 2009 and now has more than 12 million subscribers to her main channel where she talks beauty, fashion and life in general. She's followed her online success with massive sales of a series of young adult novels.
Alfie Deyes talks lifestyle, technology and gaming across three YouTube channels. He's also Zoella's other half.
Among other things, Caspar Lee interviews big-name celebrities and hangs out with other YouTubers Joe Sugg and Alfie Deyes. He was also seen in the video for Charlie XCX song "Boys".
Stylish Jim Chapman is a fashion vlogger who's been named GQ's Best Dressed Man of the Year.
Rose Dix and Rosie Spaughton are a married comedy duo who specialise in improv, and also run a gaming channel.
Up-beat mummy vlogger Louise Pentland talks fashion and motherhood on her channels.
Identical twins Niki and Sammy Albon share cooking and comedy videos on their channel.
Cooking vlogger Katie Pix guides fans through recipes, and has also worked with Jamie Oliver.
YouTube star Jack Maynard is also a TV presenter and hosts a radio show with his brother, Conor.
Identical twins Lucy and Lydia Connell recreate looks from music videos on their channel.
A friend of Caspar Lee since their schooldays in South Africa, Josh Pieters plays sketches and pranks on his channel and in Snapchat videos fro Comedy Central.
Specialising in covers on their YouTube channel, New Hope Club are a pop trio signed to a record deal by popular group The Vamps.
Mark Ferris vlogs about his life and posts videos of himself hanging out with best friend Zoella.
4.5 million fans watch Marcus Butler's comedy channel. You might also have seen him on 2016's "Celebrity MasterChef".