Hull boss Marco Silva, former Leicester manager Claudio Ranieri and Russian Leonid Slutsky have emerged as the early favourites to take over at Watford
It was announced earlier in the week that Italian Walter Mazzarri will leave the club at the end of the season.
The Hornets are searching for their ninth manager in just five years after Mazzarri's fate was sealed in a meeting with the club's board on Wednesday afternoon.
The 55-year-old Italian's final game in charge will be at home to Manchester City on Sunday with his team languishing in 16th in the Premier League, just six points above the relegation zone, but safe from the drop.
Silva, the 39-year-old from Portugal, is among the front-running candidates to take the job at Vicarage Road.
He took over from Mike Phelan at Hull in January, but despite impressing during his formative months in England, he was unable to save the Tigers from relegation.
Ranieri was sacked by Leicester in February only nine months after he guided the club to the Premier League title. Meanwhile Slutsky, the former Russia manager, has been out of work since he resigned as CSKA Moscow boss back in December.
Mazzarri's tenure at Watford started in reasonable fashion with consecutive victories at West Ham and then at home to Manchester United in September.
But the Italian has come under increasing pressure in recent weeks following the club's dramatic slump in form - they have taken just three points out of a possible 21 - and widely-publicised reports of a disgruntled dressing room.
Club captain Troy Deeney, a firm favourite among the Vicarage Road faithful, has been relegated to the bench in recent weeks, while his team-mates are said to have grown frustrated with Mazzarri's training methods and his inability to speak English.
Mazzarri, who still conducts his press conferences through an interpreter, is the seventh manager to be dismissed by the Pozzo family since they took over the club back in 2012.
Spaniard Quique Sanchez Flores was sacked by Watford last summer - despite guiding the club to the FA Cup semi-finals and comfortably retaining their status in the top division.
"After the board discussed with Walter Mazzarri the club's future goals and aspirations, it was decided he will be stepping down from his position as the club's head coach after the final game of the 2016/17 season," Watford chairman Scott Duxbury said in a short statement.
"We thank Walter and his staff for the contribution they have made to Watford Football Club over the past year."
