"On my tombstone just write, 'The sorest loser that ever lived,'" he once said.
Weaver, 82, a member of baseball's Hall of Fame and the winningest manager in the franchise's history, died late Friday while on a baseball-themed cruise, said Monica Barlow, a team spokeswoman.
The cause apparently was a heart attack, the team said on its website.
His teams won 1,480 games and lost 1,060, and his winning percentage (.583) ranks ninth all-time and fifth among managers in the modern era who managed 10 years or more.
Five times, Baltimore won at least 100 games for Weaver, who was 5 feet 7 but stood mythically tall to his players.
"Having Earl gives us a four-game lead on everybody," pitcher Sammy Stewart once said.