As Derby sack Steve McCaren only six remain
The Championship club said they had made the decision following a "thorough review of the 2014-15 season".
McClaren, 54, who has been strongly linked with the managerial job at Newcastle, joined Derby in September 2013 and led them to the Championship play-off final in 2014.
"I'm very disappointed with the decision," said former England boss McClaren in a statement.
Derby finished eighth in the second tier this season, missing out on the play-offs.
"The club means a huge amount to me, and I was not looking to leave," added McClaren.
"While we were all unhappy with the way the season ended, I still believe real progress was being made.
"I do not believe or accept that rumours linking me to the Newcastle United job were a factor in the team's performances this year, as had been alleged.
"I wanted to remain with the club and was confident in leading the side to a successful season next year."
The Rams were leading the Championship in late February but won only two out of their last 13 league games.
And their 3-0 home defeat by Reading on the final day of the Championship season left them outside the top six, having looked almost certain to be battling for promotion to the Premier League again after the previous season's near
The club statement continued: "The board believes that the appointment of a new head coach is required to continue the club's on-field progress and the search is now underway to appoint a successor.
"The board remains firmly committed and driven to achieving promotion to the Premier League."
Looking at the Championship final table only seven managers survived the season and that includes Bournemouth's promoted boss Eddie Howe. Only Ipswich, Wolves, Sheffield Wednesday, Blackburn, Middlesbrough and Rotherham currently have the same manager they started the season with.