To quote from Layne's Wikipedia page.

"Layne Thomas Staley (August 22, 1967 – April 5, 2002 was an American musician who served as the lead singer and co-songwriter of the rock band Alice in Chains, which he and guitarist Jerry Cantrell formed in Seattle, Washington in 1987. Alice in Chains rose to international fame as part of the grunge movement of the early 1990s. The band became known for his distinct vocal style, as well as the harmonized vocals between him and Cantrell. Staley was also a member of the supergroups Mad Season and Class of '99. He struggled throughout his adult life with severe drug addiction, culminating with his death in April 2002."

Alice In Chains waited more than 6 years to replace him in the band, but Layne's talent can never be matched. Here's a few videos to remember him by!