There are several bands called as Challenger:
1. A progressive heavy metal horde from Poland.The band has released a demo-album "Against The Fate"(2005).
2.A post-hardcore band on Jade Tree Records with Al Burian (Milemarker, Burn Collector zine) and Dave Laney (Media Reader zine).
3.Russian alternative metal\metalcore band from St.Petersburg. They've recorded new "DEMO", which can be downloaded at http://www.realmusic.ru/exstyx/
4.A japanese Metal project consisting of one member.