Cassius Lee Marsh Sr.[1] (born July 7, 1992) is an American former professional football linebacker.

He also played for the New England Patriots, San Francisco 49ers, Arizona Cardinals, Jacksonville Jaguars, Indianapolis Colts, Pittsburgh Steelers and Chicago Bears.

[3] He was named CIF-SS All-Northwest Division co-Defensive Player of the Year in his junior season.

[citation needed] In December 2010, he was selected to the Rivals.com Pac-10 Conference All-Freshman team in his freshman season.

[4][5] He was winner of UCLA's John Boncheff Jr. Memorial Award for Rookie of the Year in his freshman season.

[9] Marsh recorded the first sack and first forced fumble of his NFL career against the Miami Dolphins in the season opener on September 11, 2016.

[10] Week 1 on September 7 against the Kansas City Chiefs his blown coverage resulted in a 78-yard Kareem Hunt touchdown reception.

A report in 2018 said that Marsh had a locker room “tirade” and temper tantrum over playing time at halftime when the Patriots were leading 17–0 in Mexico City versus the Oakland Raiders.

[13] Marsh was claimed off waivers by the San Francisco 49ers a day after being released by the Patriots.

[15] In 2018, Marsh played in 16 games with three starts, recording a career-high 38 combined tackles and 5.5 sacks.

[24][25][26] On December 9, 2020, Marsh was signed by the Pittsburgh Steelers off the Colts' practice squad.

Curtis Sr. played two seasons for the Jaguars and one for the Pittsburgh Steelers before going to the Canadian Football League, where he was an All-Star in 2000.