California's J.R. Rotem started out working as a hip-hop producer with 50 Cent and Rick Ross, but he soon transitioned into the pop sphere. He launched the careers of Sean Kingston and Jason Derulo on his own Beluga Heights label, and he hit it out of the park with "SOS," the 2006 smash he co-wrote for Rihanna. Since then, he's become one of the industry's most in-demand producers, turning out hits for Maroon 5, Nicki Minaj, Fall Out Boy, and Meghan Trainor.