Professional career
Marshall was selected in the second round with the 37th overall pick by the New York Giants in the 1983 NFL draft. He was the fourth defensive lineman taken that year. At the time, Los Angeles Raiders managing general partner Al Davis described him as the steal of the draft.
During his rookie season with the Giants, Marshall struggled initially with weight problems, drawing the ire of the coaching staff. After trimming down, Marshall made an impact and played strongly against the run but was unable to mount much of a pass rush and finished with only 0.5 sacks on the season. He improved significantly in 1984 however, recording 6.5 sacks. He also made several key tackles to help the Giants preserve a 16–13 win over the Los Angeles Rams during the wild-card round of the playoffs.
Marshall's emergence as a pass rusher continued in 1985 as he racked up 15.5 sacks, earning him a trip to the Pro Bowl and recognition as NFL defensive lineman of the year. Marshall repeated both honors in 1986, teaming up with Hall of Fame linebacker Lawrence Taylor to form a potent pass rush on the right side of the Giants defense. He finished the year with 12 sacks, helping the Giants to a 14–2 record and an appearance in Super Bowl XXI to face off against the Denver Broncos. Marshall recorded two sacks in the Giants' 39–20 victory, earning him his first Super Bowl ring.
Marshall recorded 8 sacks in 10 games played during a strike-shortened 1987 season in which the Giants finished 6–9–1. He compiled another 8 sacks the following year as he split time with fellow defensive end John Washington. During the 1989 season Marshall collected 9.5 sacks, with the Giants losing in the first round of the playoffs that year to the Los Angeles Rams. Marshall later described the season as a lost opportunity as he felt the Giants had the best team in the league that year.
Marshall engaged in a prolonged contract holdout leading up to the 1990 season. He reported late, and after struggling initially to regain his starting job he recovered to finish the year with 4.5 sacks. The Giants went 13–3 during the regular season and advanced to the NFC Championship Game where the two-time defending Super Bowl champion San Francisco 49ers awaited them. In the fourth quarter of the game, Marshall hit 49ers quarterback Joe Montana so hard that he suffered a bruised sternum, bruised stomach, cracked ribs, and a broken hand. Montana was forced to leave the game and would not play another regular season game for almost two years (in December 1992), which ended up being his last game with the 49ers. The collision was later ranked as the third most "devastating hit" in NFL history by Fox Sports Net, and the third most "devastating hit" in sports history by The Best Damn Sports Show Period. It would also turn out to be the moment of Marshall's career that he came to be most well-known for. Marshall finished the game with four tackles, two sacks, and two forced fumbles, and was named NFL defensive player of the week. The Giants won the game 15–13 and advanced to Super Bowl XXV where they faced the Buffalo Bills. Marshall recorded the team's only sack in helping the Giants to a 20–19 victory, earning him his second Super Bowl ring.
Marshall continued to play at a high level in 1991 as he totalled 11 sacks for the year. In 1992, he clashed with new Giants coach Ray Handley however, and the two got into a well-publicized shouting match during halftime of a September game against Dallas. He ended up with four sacks on the year and entered into free agency afterwards. Marshall finished out his career playing a season each for the New York Jets and Washington Redskins.
Marshall retired from football at the age of 33. He later signed a ceremonial contract in 1996 that allowed him to retire as a Giant. Upon signing the contract he stated, "I wanted to retire as a Giant because it's where my career began. They were people who believed in my talents and helped mold me into the man I am today, and I wanted to thank them for that."
Marshall was selected to two Pro Bowls, and finished his career with 83.5 sacks in the regular season, and 7 in the postseason. His total of 79.5 as a Giant ranks him third in team history.
