This past week saw the passing of two of rock music's greatest unsung heroes, Nick Ashford and Jerry Leiber. Although maybe not household names, the songs written by Ashford, one half of husband-and-wife songwriting duo Ashford & Simpson, and Lieber, one half of Leiber & Stoller, are instantly recognizable.

Ashford & Simpson are responsible for megahits such as "Ain't No mountain High Enough" (first made famous Marvin Gaye and Tammi Terrell) and "I'm Every Woman" (made famous by Whitney Houston). Meanwhile, Lieber & Stoller wrote the eternal Elvis hits "Jailhouse Rock" and "Hound Dog," as well as the classic "Stand By Me."

So why aren't these names as famous as those who performed the hits they penned? Partially because songwriting is only one-half of the magic hitmaking formula; putting a performance, and a face, along with a great tune is often as important as the song itself.

Would "Hound Dog" be as great if it were performed by the nerdy, balding Leiber? Tough to say. The legendary Carole King, a mousy young woman who had spent years behind the scenes penning hits at the legendary Brill Building production studio (where Leiber also worked) before attaining solo success in 1971, was able to make it work. Kanye West, the wind beneath Jay-Z's wings for many years, is another example of a great songwriter exploding from behind the scenes.

However, many songwriters, among them Ashford and Leiber, just remain behind the curtain, churning out amazing hits over the course of careers that often last decades longer than the artists they've written for. Their legacies are not in their names, but in their art.

To that end, we've collected a list of 10 more great songwriters you might not have heard of, but whose hits you can probably sing along to without thinking twice. Click on the jump and prepare to be surprised. Turns out the guy who wrote "Livin' On A Prayer" also wrote "Thong Song." Bet you didn't see that one coming.