The president and COO of Island Def Jam Music Group and one of LA Reid's former key deputies, Bartels is the man who brought you The Killers, Kanye West, and Justin Bieber and who breathed new life into the careers of Melissa Etheridge and nutty pop diva Mariah Carey.

One of LA Reid's longtime chums, the pair both moved from Arista Records—where Bartels was serving as VP of promotions and special markets—to Island Def Jam in 2004. Although Bartels isn't known for his creative chops and ability to schmooze with the talent, having left that up to LA, he handled most of the business operations that led to Mariah Carey's comeback and signing fresh acts like Rihanna. However, when LA left the group in 2011 to pursue his bid at TV stardom, many feared that the creative void would be detrimental, but Bartels, along with CEO Barry Weiss, has soldiered on, and with Bartel's keen ability to build promotional strategies, the label has seen an increase in record sales and radio play, thanks to high-profile acts like Kanye West and Justin Bieber. [Image via Getty]