The St. Louis Cardinals had the best regular season record in 2005, going 100-62. http://mlb.mlb.com/mlb/standings/index.jsp?ymd=20051002 (full standings for 2005)
Your Answer: Houston Astros
That was the St. Louis Cardinals at 100-62. In the American League, the Chicago White Sox had the best regular season record at 99-63.
The team with the best regular season record in 2004 was the Pittsburgh Steelers at 15-1.
The Vikings had the best regular season record in 1998 at 15-1.
The Packers' best NFL regular season record was in the 2011 season, when they went 15-1.
The Astros best regular season record was 102-60 in 1998. They were defeated by the San Diego Padres in the NLDS that season, 3 games to 1. The Astros only World Series appearance was in 2005 where they lost to the Boston Red Sox, 4 games to 0. Their regular season record in 2005 was 89-73.
The Boston Celtics regular season record was 68-14 in the 1972-73 season.
The Miami Dolphins won Super Bowl VII after posting a regular season record of 14-0.