Australian chanteuse Sia has been releasing albums since the late-'90s, but it was during the '10s that she turned into a hit-writer-for-hire. Kylie Minogue, Rita Ora, and Rihanna have all benefitted from her knack of conjuring up catchy hooks, while her own vocals have assisted Eminem, Flo Rida, and David Guetta with crossover smashes.