When Glee aired its first episode in May 2009, the TV show only attracted a fraction of the viewers who tuned in for American Idol, which was shown on the same channel just one hour prior. The numbers looked bleak, but Billboard's music charts told a different story the following week, when the Glee version of Journey's "Don't Stop Believing" became a Top Five hit. Performed during the pilot by the castmates themselves, the song eventually sold over 700,000 downloads and paved the way for Glee's success -- not only as a television show, but also as a chart-topping recording entity. Columbia Records became Glee's official music partner that spring, and the show continued churning out hit singles when it returned in September for the full run of its first season. Of course, it didn't hurt that many of the actors had already cut their teeth on Broadway, including Lea Michele (the star of Spring Awakening) and Matthew Morrison (the original Link Larkin in Hairspray). Such experience helped boost the musical performances on the show, and Columbia began gathering some of Glee's best moments for a series of albums, beginning with Glee: The Music, Vol. 1 in November 2009. That album cracked the Top Five during its first week of release, paving the way for the arrival of Vol. 2 in December. Both records went gold; by the following year, Vol. 1 had climbed up to platinum status. Glee took a quick break at the end of 2009, with more episodes planned for the spring. The show returned in April 2010, its arrival punctuated by the release of a new soundtrack, The Power of Madonna. Featuring seven songs originally recorded by the Material Girl, the EP also introduced the newest member of Glee's cast, Jonathan Groff, who had previously performed alongside Lea Michele in Spring Awakening. It debuted at number one -- the first of Glee's releases to do so -- and was followed two weeks later by another album, Showstoppers, which also topped the charts. The show wrapped up its first season that summer, but not before releasing one final EP, Journey to Regionals, which marked the final appearance for Groff. Several months later, Glee returned with a new season and a new round of releases, including a Halloween-themed EP (The Rocky Horror Glee Show), a holiday record (The Christmas Album), and the full-length Vol. 4. Along with newcomer Chord Overstreet, the albums also featured Darren Criss, who joined the show mid-season and helped Glee earn another Top Ten hit with "Teenage Dream," as well as guest star Gwyneth Paltrow. By Thanksgiving, the cast had racked up more than 90 singles on the Billboard Hot 100, breaking the Beatles' previous record for the most hit songs by a non-solo act. Glee took home three Golden Globes in early 2011 and began turning over a new leaf with the spring release of Vol. 5, which featured the show's first pair of original songs (including the Top Ten hit "Loser Like Me"). More changes arrived with the release of The Warblers, a short album that focused exclusively on Darren Criss and his all-male choir at the fictional Dalton Academy. Glee's second season wrapped up in May 2011, one day after Vol. 6's release. A spinoff TV show, The Glee Project, immediately hit the air, followed two months later by the franchise's first movie, Glee: The 3D Concert Movie. The film documented the North American half of Glee's 2011 tour, combining behind-the-scenes footage with live performances. Glee: The Music, The Christmas Album, Vol. 2 was released that November, a couple of months after the show's third season premiered. Just a few weeks later, Vol. 7 of Glee: The Music arrived, featuring music from the first part of the third season. Mid-2012 saw the release of Glee: The Music - The Graduation Album, which commemorated the senior year of many of the show's favorite characters. The cast rounded out the year by releasing the first set of songs from the show's fourth season and a third volume of Christmas music. The July 2013 death of cast member Cory Monteith cast a pall on the beginning of the show's fifth season, but it returned that September with a tribute to the Fab Four that was released as Glee: Sings the Beatles. During the fifth season, Glee began releasing EPs of songs from each episode, including that October's Quarterback, which featured some of the Monteith tribute episode's most heartfelt musical moments, including Rent's "Seasons of Love," the Pretenders' "I'll Stand by You," and Bruce Springsteen's "No Surrender." Another Christmas album, a compilation commemorating the series' 100th episode and several EPs (including City of Angels, Tested, and Movin' Out) were among the other collections of featured music from the fifth season. Glee's sixth and final season began in January 2015, and along with it came more EPs, including We Built This Glee Club and the collection of music from the series finale Dreams Come True. ~ Andrew Leahey, Rovi