Uh-oh, Justin Bieber; the wrath of Headbanger Nation has fallen upon you.

"What Do You Mean?" singer Bieber caused outrage among Metallica fans this week, when he appeared on "The Ellen DeGeneres Show" wearing a T-shirt sporting the band's name.

The criticism came from a number of fronts. Some fans took exception to the fact that the Canadian pop heartthrob doesn't exactly seem like a fan of the group.

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"Justin Bieber singing 'Sorry' on The Ellen Show while wearing a Metallica t shirt is probably the least metal thing to have ever happened," one detractor hissed.

Another even wished death upon the singer, tweeting, "Does Bieber think he's cute wearing a Metallica shirt on Ellen? … God I hope this kid ... dies soon."

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"Justin Bieber isnt allowed to wear a metallica shirt," offered another non-Belieber.

All fair points, though none of the Bieber-haters seemed to have noted that the only thing less metal than Justin Bieber wearing a Metallica shirt on "The Ellen DeGeneres Show" is, perhaps, watching "The Ellen DeGeneres Show" in the first place.