A song murdered by someone.

Five Finger Death Punch - House of the Rising Sun.  Best version ever - Frigid Pink.

"No Mr. Nice Guy," the Pat Boone album of metal done his way is a HIGHLY coveted album and hard to get without paying pretty big bucks.  It is really quite a laugh listening to that one.  

I have not heard the "House of the Rising Sun" mentioned above, but any version will find tough competition from Andy Griffith's version of that song.  

As long as you are not in danger from laughing to death, you should then move on to Mae West singing "Twist and Shout."

Any version of "Unchained Melody" outside of the Platters.
Lauren Hill with her idiotic warbling of "Killing Me Softly".
Any remake of "What You Won't Do For Love" by Bobby Caldwell.

I love the Concrete Blonde "Everybody Knows."   I have it on the soundtrack album for "Pump Up the Volume."  There are LOTS of terrific covers of Leonard Cohen songs.  Mostly because the songs are well written, but it is also probably the case that his performance will not fit everyone's taste, so his version does crowd out contenders.

I particularly like an R.E.M. cover of "First We Take Manhattan."