The Indianapolis Colts
Tampa Bay Buccaneers with 26 consecutive losses in 1976-1977.
26 consecutive losses by Tampa Bay from 1976-77 http://www.football.com/nfl/records/NFLTGamesLost.shtml
the new york knickerbockers, with 13
American League- 21 consecutive losses by the 1988 Baltimore Orioles National League- 24 consecutive losses by the 1899 Cleveland Spiders (since 1900, the 1961 Philadephia Phillies 23 in a row)
Northwestern wildcats - 30 1980