Before they were famous pop singers and global R&B stars, the artists on this playlist were just a golden voice emanating from the unstoppable hook of a runaway hit song. Aloe Blacc is the latest to jockey for our attention with a killer hook: After years of earning underground respect and critical acclaim as a just-under-the-radar soul singer, he burst onto the main stage as the voice of Avicii's "Wake Me Up." Similarly, artists like Dido, Future, Janelle Monae and even Pharrell Williams, who were already somewhat established in particular genres or behind the scenes, made the leap to the mainstream by lending their vocals to "Stan," "Loveeeeeee Song" (among others), "We Are Young" and "I Just Wanna Love U," respectively. Others, like Bruno Mars, Anthony Hamilton and Mary Lambert, made their debuts on the pop charts on the merits of their vocal contributions to the hits "Nothin' On You," "Po' Folks" and "Same Love," respectively. And still others never quite parlayed their hook jockeying into superstardom, but still managed to carve out a niche for themselves in pop music history by voicing an iconic song's chorus (we're looking at you, Shawnna and -- so far -- Skylar Grey). Press play for these and other classic, memorable, can't-quit-'em hooks.