Emperor is a Norwegian black metal band formed in 1991, regarded as highly influential by critics and emerging black metal bands. The group split up in 2001, but reunited from 2005 to 2007 for a few festival dates and brief US tours, and again reunited in 2013 to 2014. The group was founded by Ihsahn (guitar/vocal) and Samoth (then, drums).
Had Norwegian black metal band Emperor not split up in 2001, they could not have reunited in 2005.