A Nigerian neuropathologist who discovered evidence of CTE in Mike Webster’s brain during an autopsy in 2002, sparking awareness of football-related brain damage despite initial resistance from the NFL.

A neurosurgeon and former team physician for the Pittsburgh Steelers, known for advocating the link between concussions and brain damage, supporting Bennet Omalu's research and contributing to the NFL's concussion discussions.

A prominent neuroscientist and sports medicine researcher, formerly an athletic trainer for the Pittsburgh Steelers, whose work at the University of North Carolina highlighted the connection between repeated concussions and long-term cognitive issues.

A neuropathologist specializing in tau protein who joined Chris Nowinski’s Sports Legacy Institute to study CTE, finding the disease in the majority of NFL brains she examined.

A former football player and professional wrestler who became a concussion activist, co-founded the Sports Legacy Institute, and played a key role in bringing the concussion crisis to public attention.

The NFL Commissioner from 1989 to 2006, initially skeptical of the connection between football and brain damage, under whose leadership the NFL formed the Mild Traumatic Brain Injury Committee.

NFL Commissioner from 2006, who faced the concussion crisis upon taking office and eventually implemented rule changes and improvements to research and retirement plans in response to emerging evidence.

A neurologist associated with the NFL's MTBI Committee, known for his denial of the link between concussions and long-term brain damage, and for his controversial "Dr. No" stance.

A Hall of Fame quarterback whose career was affected by multiple concussions, becoming one of several notable players in the 1990s forced into retirement due to repeated head injuries.

A Pro Bowl safety for the Chicago Bears in the 1980s who later committed suicide, leaving a note requesting his brain be studied for research, eventually revealing he had CTE.

A Hall of Fame linebacker known for his outstanding career and community involvement, whose post-retirement struggles culminated in his suicide, with CTE later confirmed in his brain.

A pioneering sports agent who represented prominent NFL quarterbacks affected by concussions, raising awareness about their growing severity by hosting informational seminars in the 1990s.

A former NFL running back who suffered career-ending concussions and later sued the Chicago Bears over mishandled injury management, highlighting gaps in concussion protocols.