Deacon Jones, defensive end...

...for the Los Angeles Rams, died at age 74. A member of the team's legendary "Fearsome Foursome," Jones changed the NFL in two important ways:

He pounded opposing quarterbacks, rolling up dozens of sacks, and he popularized the head slap to dominate offensive linemen. 

"The Secretary of Defense" had so many "sacks," in fact, that they became an official statistic in 1982. And as for the "head slap," they were so effective that the League outlawed them after Jones retired.