Unexpected Cover: Ghost - Here Comes The Sun
Everyone who hasn't been living under a rock for their entire lives obviously knows who the Beatles are. Most people in metal circles are at least aware of the occult rock/metal band Ghost. Many love them. However, they have many detractors who say their music is to polished, poppy and clichéd. I kind of think these people are over thinking it - they are good simple fun.
It may come as a surprise that they chose to cover the Beatles, nevertheless one of their most upbeat and happy songs. A band that is good at doing covers can change the song into something else while not making it sound silly or out of place. This is exactly what Ghost does, turning it into creepy keyboard driven occult rock, which turns out to be highly enjoyable.