Quique Sanchez Flores insists Watford will remain in his heart forever, after becoming the second English Premier League manager sacked by the struggling club this season.
The Hornets sacked the Spaniard less than three months into his second reign, after a poor run of results that saw them win only one of their 10 league matches.
Flores was only reappointed in September, replacing Javi Gracia four games into the campaign.
"With regret, Watford Football Club confirms the departure of head coach Quique Sanchez Flores," the club said in a statement.
Watford has not named a replacement, but said an announcement was imminent, with British media reporting that former Brighton & Hove Albion manager Chris Hughton was the leading candidate.
The Hornets are bottom of the Premier League with eight points from 14 games.
"I would love to say a big thank you from my heart for the appreciation, respect and support that I've felt in each moment I've lived in the lovely family that Watford is," Flores said in a statement.
"This is not the time to think about individual feelings, it's time to have a collective reaction... I wish you all the best. Stay strong!"
Since Sean Dyche's departure in 2012, when the Pozzo family took over ownership of the club, 10 managers have come and gone - including Flores twice - of whom only Gracia lasted more than one season.
Flores was previously in charge of the club during the 2015-16 season, after which he was surprisingly sacked.
During Flores's 85-day-spell at the helm this year, Watford's solitary league win came against promoted Norwich City last month.
He oversaw five league defeats - including an 8-0 humbling by champions Manchester City - and his last game in charge was Saturday's 2-1 defeat at Southampton.
Watford's next game is a league trip to second-placed Leicester City on Wednesday.