The Raiders gave no details of the death of one of the leading personalities in the NFL but said a statement would be made later on Saturday on the site (http://www.raiders.com).
Davis was hired as coach and general manager of the Raiders at the age of 33 and later became principal owner.
The Raiders won three Super Bowls and had 28 winning seasons, including 16 in a row from 1965-1980, during his 48 years with the team.
Davis was also commissioner of the American Football League in 1966 and was viewed as a driving force in its merger with the NFL.
"Al Davis's passion for football and his influence on the game were extraordinary," said NFL Commissioner Roger Goodell in a statement.
"He defined the Raiders and contributed to pro football at every level. The respect he commanded was evident in the way people listened carefully every time he spoke.
"He is a true legend of the game whose impact and legacy will forever be part of the NFL," Goodell said.
Davis could also be defiant. After a lengthy court battle, he took the Raiders away from Oakland to Los Angeles from 1982 to 1994 before returning the franchise to its original home.
He was inducted into the Pro Football Hall of Fame in 1992.
Although his team has struggled in recent years, Davis led one of the most successful franchises in sports during the 1960s and '70s.
Like their iron-fisted boss, the Raiders were the tough guys of the NFL in their silver and black uniforms.
"I judge sports figures based on individual achievement, team achievement and contributions to the game," Davis told reporters when George Steinbrenner, owner of baseball's New York Yankees, died in 2010.
"George was right up there with me at No. 1 -- bright, aggressive and, most of all, not afraid."
The trailblazing Davis was the first NFL owner in the modern era to hire a black head coach, Art Shell in 1988, the first to name a Hispanic head coach, Tom Flores in 1979, and the first to name a woman as chief executive, Amy Trask.
"What a tremendous person, tremendous man," current coach Hue Jackson told reporters in Houston where the Raiders play on Sunday. "I owe him so much. This league owes him so much. He's a legend and an icon."