I thought this might be an interesting topic: What was the first
song (not necessarily a complete album) in each of these genres:
1. doom metal
2. power metal
3. thrash metal
4. death metal
5. black metal
6. grunge

7. emo
Since I have less musical knowledge than many others here, I will not attempt to pontificate on the 'first', except to hazard a guess that the first doom song was 'Black Sabbath'.