headbanger

noun7

1. •
   One who dances by violently shaking the head in time to the music.
2. •
   One who enjoys heavy metal (rock) music, to which this sort of dance is usually performed.
3. •
   A violently deranged, extreme or fanatical person; a nutcase.
4. •
   (UK) A political hardliner, especially an obstructive one.

   • Corbyn's lack of ambition would turn out to be one of his great selling points. He was the man at the margin: a headbanger for most and a man of principles for a few. — 2021
5. •
   A silly or eccentric person.
6. •
   (Northern-Ireland) A person who engages in street violence, especially in support of a political group.
7. •
   A kind of chin-up or pull-up exercise where the head is kept in line with the bar.