A co-founder of Mastodon – along with guitarist Bill Kelliher, bassist Troy Sanders, and drummer Brann Dailor – Hinds was a major figure in pushing metal guitar, and metal as a whole, into uncharted territory in the 21st century – challenging the genre’s rules and conventions with playing that bore the mark of a wide range of influences.

Mr. Hinds, 51, was found unresponsive late Wednesday after an S.U.V. appeared to slam into the motorcycle he was riding near downtown Atlanta, the authorities said.