Marvin Lewis has left the Cincinnati Bengals after a 16-year spell as head coach on 'Black Monday' - a day of sweeping changes in the NFL.
A third successive losing season saw a change made, with the Bengals now seeking a new head coach for the first time since 2003.
Denver Broncos, Arizona Cardinals and Miami Dolphins also changed their head coaches on Monday after a failure to make the end of season play-offs.
Cincinnati said the decision to remove Lewis was mutual, after 131 victories in his term as boss, which included seven visits to the play-offs.
"I want to thank the Bengals' organisation, the fans and the city of Cincinnati for their support," Lewis said on bengals.com.
"I regret I haven't been able to provide them with the number one goal of being world champions."
Denver's first consecutive losing seasons since 1971-72 saw Vance Joseph's time in charge come to an end.
Joseph's two seasons in charge featured a record of 11 wins and 21 losses.
President of football operations/general manager John Elway said on denverbroncos.com: "There's always going to be a high standard here - the bottom line is we need to win more football games."
Adam Gase was fired by Miami after three seasons with a record of 23 wins and 25 losses.
Dolphins owner Stephen Ross promoted Chris Grier from general manager to head of football operations.
Steve Wilks served only one season as head coach of Arizona Cardinals, but a record of three wins and 13 losses saw his tenure end.
The moves follow head coach departures for New York Jets and Tampa Bay Buccaneers, who fired Todd Bowles and Dirk Koetter, respectively, on Sunday.