People have only mentioned Irish bands so far. Probably because their bands are in general far more known than bands from the other countries (IMO Ireland has the best metal scene these days).
Irish bands not yet mentioned:
Carnun Rising (old school death metal)
Old Season (trad doom)
Wreck of the Hesperus (funeral doom)
Scald (avant garde metal)
Waylander (folk metal)
Scotland:
Man Must Die (brutal melodeath)
Regorge (brutal death)
Serenade (sludgy doom)
Ordog (weird raw black metal)
Korpse (death n roll)