Manager Phillip Cocu has left Derby by mutual consent, the Sky Bet Championship club have announced.
Dutchman Cocu took over as Rams boss during the summer of 2019 following the departure of Frank Lampard to Chelsea.
However, Derby have managed just six points this season, and sit bottom of the table.
Derby confirmed assistant manager Chris Van Der Weerden and specialist first-team coach Twan Scheepers have also left their roles.
A statement on the Derby website read: "The club would like to place on record its appreciation for the way Phillip and his staff conducted themselves in what were some extremely challenging situations during his tenure.
"Phillip and his staff helped develop and establish a considerable number of academy players in to the first-team squad and Phillip made significant financial contributions and personal efforts towards the club's community projects during the Covid-19 pandemic, which the club are extremely grateful for.
"Derby County wishes to thank Phillip, Chris and Twan for their hard work and dedication over the last 16 months and wish them every success in their future careers.
"The club will provide further updates when appropriate and will be making no further comment in the meantime."
Former England captain Wayne Rooney joined the Rams in January as the 35-year-old looked to take his first steps into coaching while also continuing his playing carer.
Following Cocu's departure, it has been suggested the ex-Everton and Manchester United forward could now be set for a more senior backroom role.
Earlier in November, Derby confirmed a deal had been agreed "in principle" for the sale of the club to Derventio Holdings, which is owned by Sheikh Khaled Zayed Bin Saquer Zayed Al Nayhan, a member of the Abu Dhabi Royal Family.
Sheikh Khaled is the cousin of Manchester City owner Sheikh Mansour Bin Zayed Al Nahyan, and the deal to buy Derby is reported to be in the region of £60million.
