I'm voting Venom for Newcastle, they arguably invented and/or influenced all extreme metal, and most regular metal from the thrash-era onwards as well.

Which, considering they could barely play and were basically just some pissed-up Geordies arsing about and recording their greatest work in a glorified garage in Wallsend is pretty good going.

http://www.youtube.com/watch?v=oYtVb48fvY0
http://www.youtube.com/watch?v=Eg93GhOfTQI
http://www.youtube.com/watch?v=_Sb46VD5CmA

you do you have?