The Englishman lasted just nine months at the City Ground after replacing Philippe Montanier and leaves them 14th in the Championship after a 1-0 defeat to Sunderland on Saturday made it four games without a win.
Here, Press Association Sport takes a look at who could be the new man in the hotseat.
Still considered one of the brightest young English managers in the game despite his recent dismissal at Middlesbrough, Monk is certain to be in the frame. His sacking came just two days before Christmas and following a win at Sheffield Wednesday that left the Teessiders just three points out of the play-off places. Monk enjoyed an impressive season at Leeds in 2016/17 and has Premier League experience with Swansea.
It is surprising that the man who Monk replaced at the Riverside is still out of work after guiding Boro to the Premier League in 2016 but he was dismissed as they battled relegation last season. The former Real Madrid number two’s style is not always easy on the eye but after a long spell in the doldrums, it is likely that results rather than aesthetics will be at the forefront of any recruitment strategy. The Spaniard is still based in the north of England and has stated his desire for a new project.
Another man with experience at the top end of the Championship is Poyet after his successful spell at Brighton. He guided the club to the League One title before finishing in the Championship top 10 and then making the play-offs but left the club under a cloud due to off-field matters. A short spell at Sunderland followed before a move to LaLiga and two seasons at Real Betis. He resigned from his post at Shanghai Shenhua in September but is seen as an excellent motivator and could provide the spark Forest need.
Currently seemingly happy in the relative footballing backwater of the Belgian second tier with OH Leuven, Pearson is a name linked with every Championship job that comes up, and with good reason. He has twice guided Leicester to promotion – once from the second tier in 2014 – and also has Championship experience with Southampton, Hull and Derby. His ill-fated spell at Forest’s biggest rivals was his last job in English football but crossing that divide has never proved a huge problem historically.
The son of Forest great Brian, Nigel Clough is always linked with the position and had talks in January before Warburton was appointed. Finished off the job started by Jimmy Floyd Hasselbaink by getting Burton promoted in 2016 and did an excellent job of keeping them up on a shoestring budget last term. His four-and-a-half years at Derby in the Championship were steady if unspectacular but with over 100 goals for the Trees as a player and his second name, Clough Jr can never be ruled out.
Uwe Rosler was sacked by Fleetwood following a 3-0 reverse at Doncaster which condemned Town to a seventh straight defeat in all competitions.
Cambridge interim head coach Joe Dunne was pleased with how his side adapted to beat Grimsby 3-1.