There are and have been several bands named Gehenna, the most notorious of which are the following:
1) A black metal band from Norway.
2) A blackened hardcore band from Reno, Nevada, USA (also known as THE INFAMOUS... GEHENNA)
1) A black metal band that was formed in Stavanger, Norway in January 1993 as a nameless project by Sanrabb, Dolgar and Sir Vereda. They didn’t give the band a name until they had enough material which would represent their voice.