As far as all time winning percentages go, through 15 games of the 2009 season that would be the Houston Texans who have an all time regular season record of 48-79 for a winning percentage of .378.
The Tampa Bay Buccaneers have the second lowest all time regular season winning percentage at .393 (208-322-1) and the Atlanta Falcons are third lowest at .414 (275-390-6).
The Houston Texans.
The Detroit Lions.
The NFL team with the worst overall record in 2008 was the Detroit Lions, who were 0-16.
The team with the worst record get the first overall pick and so on.
The 1976 Buccaneers.
The Tampa bay Bucaneers
The Detroit Lions have been called the worst team for this decade.
The Houston Texans, with a record of 2-14, had the worst season in the 2013 NFL regular season.