A former Christian artist who ditched the sacred sounds of CCM for a secular mix of sass and spunk, Katy Perry combines the cheeky, club-ready pop music of Lily Allen with the commercial pop/rock of Avril Lavigne and Alanis Morissette. Perry released a self-titled Christian album in 2001 under the name Katy Hudson. She would later abandon the genre in favor of a pop career. Her debut single, "UR So Gay," generated some online buzz with its mischievous lyrics and accompanying music video. However, "I Kissed a Girl" proved to be her true breakthrough single, topping the charts in 20 countries and pushing its accompanying album, 2008's One of the Boys, into the Top Ten in America. Meanwhile, "Hot N Cold" became her second number one hit and "Waking Up in Vegas" cracked the Top Ten. Such success meant that Katy Perry had officially become one of the industry's biggest pop stars, celebrated as much for her outsized behavior and outrageous fashion choices as the music itself. She continued touring through the summer of 2009 and found time to tape an installment of MTV Unplugged, which was released in November. Meanwhile, she worked on a new album and started up a whirlwind romance with comedian Russell Brand, eventually becoming his fiancé. Recording sessions for her album wrapped up in early 2010, and Perry scored her second number one single with “California Gurls,” which was released that May. The accompanying album, Teenage Dream, followed in August.