Katy Perry performs live in concert during 'The Prismatic World Tour' at O2 World

Justin Bieber celebrates his 21st birthday at Omnia nightclub inside Caesars Palace Hotel & Casino

Kylie Jenner enjoys a late night visit to Topshop in Westfield during her trip to the UK

A brightly dressed Cate Blanchett arrives at the Australian premiere of Disney's Cinderella

Girls star Lena Dunham arrives at the Ed Sullivan Theater for 'Late Show with David Letterman'

Heidi Klum Intimates Launch at Bloomingdale's

Gwen Stefani visits the Jesun Acupuncture Clinic in LA

The Script perform live in concert during a sold out show at The O2

Charli XCX performs live in concert at O2 World

Ashley Greene keeps it real by wearing gym clothes and no make-up while out and about

Kanye West arrives at Los Angeles International Airport (LAX)

Actress Halle Berry dresses down as she arrives on the set of 'Extant' filming in downtown Los Angeles

Cover Girl Victoria Justice Hosts Kode Mag Spring Issue Release Party

Sam Smith at the London Palladium for Comic Relief

Orlando Bloom at the London Palladium for Comic Relief

Lenny Kravitz and ex-wife Lisa Bonet go for lunch together at Gracia Madre Restaurant in Beverly Hills

Jessica Simpson arrives at the Teen Vogue 10th Annual Fashion University

Cody Simpson at the The Ultimate Spring Break Bash hosted by Victoria Secret PINK Nation

Charlize Theron attends the 2015 Australian Formula One Grand Prix