Kevin Turner, a lead plaintiff in a concussion-related lawsuit brought by more than 5,000 former players against the N.F.L., died on Thursday. He was 46.

He had been treated for amyotrophic lateral sclerosis, or A.L.S., for six years.

Turner, a star running back at Alabama who played for eight years in the N.F.L., for the Philadelphia Eagles and the New England Patriots, was one of the loudest advocates in the case against the league, which was accused of hiding the dangers of concussions and head hits from players.

In 2013, the N.F.L. reached a settlement with the players that was approved by a federal district court judge in 2015.

“It’s about helping people who had their brains affected in a very drastic way, and to make their lives so much more livable, not just them but their families, and to supplement their health care,” Turner told The New York Times in 2014.