Hellhammer was a Swiss extreme metal band from Nurensdorf, active during 1981–1984, in June 1984, Hellhammer disbanded and founded another highly influential band, which Swiss heavy metal band, from Zürich?
Hellhammer:  In June 1984, Hellhammer disbanded and founded another highly influential band, Celtic Frost. Celtic Frost: Celtic Frost ( ) was a Swiss heavy metal band from Zürich.
Celtic Frost