Bell, whose announcement came from the OSU sports information department, was a two-year starter at safety for the Buckeyes. He was a first-team All-American in 2015 and finished his career with 176 tackles and nine interceptions.
Linebacker Darron Lee made his announcement Saturday night while safety Tyvis Powell followed Sunday morning.
Apple was a four-star recruit at Voorhees Eastern High in New Jersey in 2013. He redshirted his first year in Columbus and had been a starter the past two seasons.
He was named the defensive MVP of the Buckeyes’ win over Notre Dame in the Fiesta Bowl.
Marshall was Ohio State’s No. 2 receiver in 2015 when he made 36 catches for 477 yards and five touchdowns. The former five-star recruit from Middletown, Ohio, was also the team’s primary punt returner, averaging 13.5 per attempt.
Lee and Powell were three-star recruits from Ohio who redshirted and worked their way into productive college players and starters for the 2014 national champions.
Powell ended up third on the 2015 team with 71 tackles. He also had three interceptions.
Lee was fourth with 66 tackles, including 11 for loss and 4.5 sacks. He had an interception and forced two fumbles.
Three juniors previously declared for the draft: defensive end Joey Bosa, running back Ezekiel Elliott and quarterback Cardale Jones.
Ohio State’s 2016 draft early-entry class is the largest in school history by far.
The most Buckeyes to previously leave early in one year was three. That happened in 1995 (Korey Stringer, Craig Powell, Lorenzo Styles) and 2006 (Donte Whitner, Santonio Holmes and Ashton Youboty).
Three Ohio State players have gone pro early so since Urban Meyer became the coach of the Buckeyes: Johnathan Hankins in 2013 with Ryan Shazier and Bradley Roby following a year later.