Paterno, who had been head coach at Penn State for 46 years, was replaced on an interim basis by his assistant coach Tom Bradley. Spanier's duties will be assumed temporarily by Rodney Erickson, Penn State provost.
Spanier's resignation had been widely expected, but Paterno's immediate removal came as a surprise to many in the university. Earlier in the day, Paterno said he would finish the season and then retire. Students gathered late Wednesday in State College to protest Paterno's firing.
"One more game!" the students chanted. They wanted Paterno to coach the season's final home game Saturday against Nebraska. Around midnight, thousands marched from downtown to Old Main shouting, setting off fireworks and beating on cars in support of "JoePa."
Two national championships. The envied graduation rate of his players. The rigid focus on academics. All of that will be remembered, but the legacy of the man behind Happy Valley forever will be linked to the role Paterno played in the sex scandal.
Paterno built his legendary coaching career, a football program considered pristine and a university in central Pennsylvania from an initial desire to raise tuition for law school. On Wednesday, that career reached a stunning conclusion amid one of the most sordid legal and moral scandals in college sports history.
The Hall of Fame football coach who built the Penn State program on the principle of "Success with Honor" announced his retirement, four days after his former assistant Jerry Sandusky was charged with 40 counts of sexual abuse of children.
Paterno, who will turn 85 in December, said in a statement Wednesday night: "Right now, I'm not the football coach, and that's something I have to get used to."
He had intended to coach the game against Nebraska, but the trustees scuttled that plan. Paterno's dismissal concludes one of the swiftest and most important falls in sport.
Less than two weeks ago, Penn State defeated Illinois for Paterno's 409th career victory, a record among NCAA Division I football coaches. Following the game, Paterno accepted a plaque commemorating the moment from Spanier and then-athletic director Tim Curley.
Now Paterno is gone and Spanier is gone. Curley has been on administrative leave since being charged with perjury in the Sandusky case.
Kevin Harley, a spokesman for Gov. Tom Corbett, said late Wednesday that the governor was not surprised by the university's action.
"The governor said [earlier Wednesday] that he wanted the Board of Trustees to act swiftly and strongly and they have done that," Harley said. "Now they need to go about the job of restoring trust and faith in the university for the students, alumni and citizens of Pennsylvania who pay the taxes that support the university."
Harley said Corbett still plans to travel to the board of trustees meeting on Thursday after an appearance in Philadelphia. He'll stay overnight in State College on Thursday night and attend the board's meeting on Friday, Harley said.
Earlier Wednesday, Paterno said he was "absolutely devastated" over the charges against Sandusky, in the statement that was drafted by his family and a Virginia-based crisis management firm separate from the university. Current players learned of their coach's retirement via social media before he addressed them at an 11 a.m. team meeting. Paterno cried at the short event, and players gave him a standing ovation.
"It's criminal the way he went out," senior offensive tackle Chima Okoli said, "because he's done so much for this university and he's had such a legacy. This isn't a fitting end for all the work he's done, not only for Penn State but for the world."
Until this week, Paterno had derived his mission and potential legacy from advice given by his late father, Angelo: "If you stay [at Penn State], have an impact."
Joe Paterno had no intentions of doing so. After playing football at Brown University, Paterno joined his coach, Rip Engle, in migrating to Penn State in 1950. He intended to coach for two years, pay off his student loans and save money to attend law school.