There are multiple bands with the name Underdark:

1) Black metal band from Nottingham, UK. Released their debut album 'Our Bodies Burned Bright On Re​-​Entry' in 2021.

2) Black metal from Ukraine. Solo project of Amorth, ex-drummer for fellow Ukrainian bands Drudkh, Thunderkraft, Lucifugum and more. (More information)

3) Death metal from Poland. Released debut album, In the Name of Chaos, in January 2010. (More information)

4) Thrash metal from Poland. Split-up in 2006.

5) Power metal from Hungary. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.