Layne Thomas Staley (born Layne Rutherford Staley; August 22, 1967 – April 5, 2002) was an American musician, songwriter and the original lead singer of the rock band Alice in Chains, which rose to international fame in the early 1990s as part of Seattle's grunge movement. He was known for his distinctive vocal style and tenor voice, as well as his harmonizing with guitarist/vocalist Jerry Cantrell. Staley was also a member of the glam metal bands Sleze and Alice N' Chains, and the supergroups Mad Season and Class of '99.

"Man in the Box", the second single from Alice in Chains' debut album, Facelift (1990), garnered Staley critical recognition for his vocal style. Alice in Chains' EP Jar of Flies (1994), debuted at number one on the Billboard 200, making it Alice in Chains' first record—and the first-ever EP—to top the chart. However, Staley's deteriorating condition due to heroin abuse led him to enter a rehabilitation clinic. He began to work on a side project with several Seattle musicians, Mike McCready of Pearl Jam, Barrett Martin of Screaming Trees and John Baker Saunders of The Walkabouts, which came to be Mad Season, while Alice in Chains went into hiatus.During Alice in Chains' hiatus, reports of Staley's drug addiction began to gain widespread circulation in fan and media communities, in part due to changes in his physical condition brought on by prolonged heroin abuse. On April 10, 1996, the band returned with a performance on MTV Unplugged in New York; it was their first concert in two-and-a-half years. From mid-1996 onwards, Staley was out of the public spotlight, never to perform live again.

Staley struggled with depression and addiction for much of his adult life and later died from a speedball overdose on April 5, 2002, at the age of 34. Staley was ranked at No. 27 on Hit Parader's list of "Heavy Metal's All-Time Top 100 Vocalists" in 2006, and at No. 42 on Complex's magazine list of "The 50 Best Lead Singers of All Time" in 2012. Seattle officially declared August 22, 2019, as "Layne Staley Day". Staley earned six Grammy Award nominations as a member of Alice in Chains.