A former 10th-round pick out of Arkansas Pine-Bluff, Greenwood was a member of a Steel Curtain defense that included Joe Greene, Dwight White, Jack Lambert, Jack Ham, Mel Blount and Donnie Shell. He played for the Steelers from 1969 to 1981 and earned four Super Bowl rings.
A six-time Pro Bowl selection, Greenwood retired with 73.5 sacks, second in franchise history. One of his best postseason performances came in Super Bowl X when he sacked Cowboys quarterback Roger Staubach four times.
Greenwood, 67, was a finalist for the Hall of Fame in 2005 and 2006 but wasn't elected in either year. According to the Post-Gazette, there has been a movement in recent years to get Greenwood into Canton via the veteran's committee.