Joseph Carl "JC" Tretter Jr. (born February 12, 1991) is an American former professional football center.

He played college football at Cornell and was selected by the Green Bay Packers in the fourth round of the 2013 NFL draft.

In basketball, he was a four-year starter for the Tigers and a three-time first-team all-league selection, and graduated as the team's all-time leading scorer and rebounder.

After playing tight end during his first two seasons, he switched to the offensive tackle position for his final two years.

[17] Having studied labor relations at Cornell University,[18] Tretter was elected President of the NFL Players Association on March 10, 2020, succeeding Eric Winston.

[19][20] He played a role in negotiations surrounding the 2020–2030 collective bargaining agreement,[21] which was ultimately agreed to five days after he became president of the NFLPA.

He represented players in negotiations that created new health and safety protocols,[23] resulting in an average league positivity rate of 0.076%[24] and enabling all 256 regular-season games being able to be played with no cancellations.