Aside from the 1972 Miami Dolphins, three NFL teams have gone undefeated and unbeaten in regular season: the 1934 Chicago Bears, the 1942 Chicago Bears, and the 2007 New England Patriots. The 2014 Seattle Seahawks were 9-0 before losing their final game of the season to reach 10-1.
In addition, the 2009 Pittsburgh Steelers went 11-0 before losing their last game of the season to finish 12-2.
The only other team to go undefeated during a regular season was the 1958 Baltimore Colts, who finished 14-0.
Since then, no team has been able to go through an entire season without being defeated. However, two teams have come close: the 2011 Detroit Lions and the 2012 Denver Broncos both went 11-5 before losing their final games of the season.
The 2013 Ravens and the 2015 Packers both had perfect records of 12-0 before losing their final games of the season. Both teams were ranked No. 1 at the time they played each other in the Super Bowl; however, neither team was able to win their first title since they became a single-division league and added more games to its schedule.
It's the ideal season. The 1972 Miami Dolphins became the first team in the post-merger NFL to complete a flawless regular season. They are the first team in NFL history to go undefeated in both the regular season and the playoffs. The '72 Dolphins outscored their opponents by a total of 244 to 22 during that span.
Other teams have gone 11-0, but only the 1972 Dolphins completed the feat without a single loss. The 2000 Baltimore Ravens and the 2001 New England Patriots are the only other teams to do so. Both teams came close to finishing their seasons with 12 wins, but they lost in the last game of the year for the Ravens and in the first round of the playoffs for the Patriots.
The 2012 Denver Broncos are the most recent team to go 11-0. With their victory over the San Diego Chargers on December 31, 2012, the Dolphins are now tied for second all time with the 1972 and 2000 Ravens for the most consecutive 10-win seasons. The 1972 Dolphins and 2000 Ravens both did it without a single loss during that span.
In addition to those two teams, four other clubs have gone 9-1: the 1906 Chicago White Sox, 1954 Cleveland Browns, 1969 Houston Oilers, and 1973 Washington Redskins. The latter three teams fell short in their attempts to become the first club to finish the season with no defeats.
The 1972 Miami Dolphins are the first NFL team to win the Super Bowl after completing a flawless season. The squad is still the only one in NFL history to go undefeated and untied from the first game through the Super Bowl (or championship game). Miami defeated the Washington Redskins 31-0 at Tulane University in New Orleans. The loss ended their season.
In 1992, the Buffalo Bills became the first team to go an entire regular season without losing a game when they beat the Houston Oilers 28-24 in overtime of the final game of the season. The following week, Buffalo defeated the New York Giants 21-16 to win the division title and a spot in the playoffs. It was also at this time that the concept of winning games in double overtime began.
In 1997, the Denver Broncos completed a 14-2 record as winners of the AFC West. They went on to defeat the Atlanta Falcons 34-19 in the 1998 AFC Championship Game before defeating the Pittsburgh Steelers 41-10 in Super Bowl XXXII. This was the first Super Bowl victory for head coach Mike Shanahan and quarterback John Elway.
In 2014, the Seattle Seahawks became the first team to go an entire regular season without losing when they defeated the San Francisco 49ers 29-22 in the NFC Championship Game.
In NFL history, 11 teams were winless after playing at least eight games. In comparison, nine NFL teams, including those with ties, went unbeaten throughout the regular season. The 2008 Detroit Lions were the most ineffective NFL team in history.
The 1930 NFL season was the first season in league history that didn't feature at least one winless team, and only one team went without a victory throughout the decade, that being the 1934 Cincinnati Reds, who folded before the year was over.
There are 11 teams in NFL history that went winless after playing in at least eight games. In comparison, there are nine NFL teams that went undefeated during the regular season, including teams that had ties. The 2008 Detroit Lions were the most futile NFL team of all time. The 2008 Lions went 0-16, setting the NFL record for most losses in a season. They also led the league in turnovers committed (75). The 1997 San Francisco 49ers and 1954 New York Giants are the only other teams to go winless. The 1997 49ers lost their first six games before beating Washington in Week 7 for their only victory. The 1954 Giants lost their first seven games before losing five straight to close out the season. Each of these teams was owned by an American football club that no longer exists.
An NFL team goes winless when it loses every game in a season. This has never happened but it is possible with a perfect storm of events occurring all at once. The 2007 Pittsburgh Steelers are the only team to go winless while still having a chance to win the championship. They started 3-0 but then lost their next five games to end up with zero wins.
The 2016 Cleveland Browns are the most recent team to go winless. They failed to win any game during the 2017 season and were eliminated from playoff contention after week 14. Prior to this season, the last time a team went winless was in 2014 when the 2-14 Tampa Bay Buccaneers came into existence.
The Dolphins of Miami Only one team has played a flawless season (including regular season and playoffs) since the National Football League's inception in 1920: the 1972 Miami Dolphins, who won all fourteen regular season games and three postseason games, including Super Bowl VII, to conclude the season 17-0-0. They are the only team to date to finish a season undefeated.
In addition to finishing the season undefeated, the 1972 Dolphins also hold the record for most consecutive wins (12), most consecutive road victories (9), and longest winning streak of any post-season participant (4). They also have the distinction of being the first champion from a new city when they were awarded the AFC East title after the 2001 season based on their record (10-2).
The last team to go through the season unbeaten was the Chicago Bears in 1970. The Patriots are the only other team to go through the season without losing a game.
Both the Bears and the Patriots made it to the Super Bowl but lost, giving us our first tie game in the championship round. The 1970 Super Bowl ended in a tie at 3 goals each. The Vikings would win it in overtime!
Since that time no team has gone through the entire season without losing a game. However, two teams have come extremely close: the 1999 Rams and the 2001 Ravens.
Only five NFL teams have gone winless since 1944: the 1960 Dallas Cowboys (0-11-1), the 1976 Tampa Bay Buccaneers (0-14), the 1982 Baltimore Colts (0-8-1), the 2008 Detroit Lions (0-16), and the 2017 Cleveland Browns (0-16). The Bucs and Lions are still searching for their first victory.
The last team to go winless in a season was the 1956 Brown Bears, who were 0-12. That team was also removed from the league after that season. The current winless team is the 2017 Cleveland Browns, who lost their first game 21-0 to Pittsburgh. The Browns don't have any more games left on their schedule, but if they lose again next week against the New York Jets, they will be officially eliminated from playoff contention.
In addition to the Browns, another winless team from 2016 remains in the playoffs. The 2-14 Rams had been ranked as high as fourth before losing their final four games of the season. They're out of the playoffs despite having one of the most productive offenses in football this year because they couldn't beat even one good team. Los Angeles lost to both the Seahawks and 49ers during the season.