Six-String Samurai, imagine if Elvis was literal King of Las Vegas, dies and leaves a power vacuum that send numerous baddies on a mission to become king, and Buddy Holly can not only play the axe, he can handle a katana blade even better. In hindsight this could just be a fallout movie with a few tweaks.

Honorable Mention: Wild Zero, very loud Japanese punk band Guitar Wolf takes on zombies with their instruments and maybe some magic?

Honorable Mention 2: Delivery, a pizza delivery driver is shit on constantly by everyone around him until he snaps and basically kills everyone who fucks with him.