Bliix

Bliix is a youtube artist, who makes mainly metal covers of popular songs. He gets dozens of suggestions every day. He has made metal remixes of Lady GaGa, Britney Spears, Ke$ha, Pitbull, Pussycat Dolls, Snoop Dogg, Eminem, and so on.
Usually the reason for not making a cover for the song is that the song is either not suitable for his style or there is no studio acapella/instrumental available and the original track wouldn't work at the background. One example being Lady Gaga - Telephone.