David Wagner has left Huddersfield Town as manager by mutual consent with the club bottom of the Premier League.
The German, 47, took over as Terriers boss in November 2015 and led them to promotion to the Premier League in 2016-17 via the Championship play-offs.
Huddersfield were one of the favourites for relegation last season but Wagner kept them up with a 16th-place finish.
They have struggled this season, with just 11 points from 22 games, and are eight points adrift of safety.
Wagner's departure a 'truly joint decision'
Town chairman Dean Hoyle called it a "sad day" after Wagner's achievements took him among the "greats" of the club.
Hoyle said in a statement: "I would like to begin by thanking David for all he has achieved at Huddersfield Town over the last three-and-a-half years.
"Under his stewardship, we have achieved things on the football pitch that surpass anything in modern memory, and that have gone well beyond my wildest expectations as chairman and as a fan.
"Under David's management, we took this club to the highest position it has held in almost 50 years and created memories that will last forever.
"His achievements will rightly put him up there in Huddersfield Town history alongside great names like Herbert Chapman and Mick Buxton; legendary managers who changed the face of this club.
"As I had said previously, I had no intention of sacking David this season. Subsequently David - being the great man he is - came to us and made it clear that he needs a break from the rigours of football management.
"We discussed making that change immediately, but he also made it clear that he would give his all for the rest of this season before departing in the summer if we preferred.
"After a long discussion we all felt that David staying at the club until the end of the season was best, but we've kept discussions open and we all now feel that the time is right to part ways.
"I know the term 'mutual consent' is often a byword for the manager being sacked in professional football, but this is a truly joint decision. David has a real, genuine love for this club and, like me, his foremost concern in our talks has been to establish what is best for Huddersfield Town."
Wagner's last game in-charge came in Saturday's goalless draw at fellow relegation candidates Cardiff, when the visitors were denied a late penalty.
He was named Championship Manager of the Year after leading the west Yorkshire side into the top-flight and claimed the Premier League Manager of the Month award in in August 2017.
In all, Wagner had a 33.1% win ratio from his 154 games as boss.
Coach Mark Hudson will take charge of the next league game against champions Manchester City on Sunday.
Analysis - Wagner will be remembered with great affection
BBC Sport chief football writer Phil McNulty
There was genuine warmth tinged with sadness in the words of Huddersfield Town chairman Dean Hoyle as he announced David Wagner was leaving the club by mutual consent.
And this was perfectly understandable given the scale of the charismatic German's achievements at the Terriers since he was a surprise appointment to replace Chris Powell in November 2015.
Wagner set aside the comparisons with his great friend Jurgen Klopp at Liverpool to fashion a side in his own image, full of energy, endeavour and fearlessness as they achieved what many regarded as the impossible by reaching the Premier in May 2017 after winning a Wembley penalty shoot-out against Reading.
If this was not enough, he produced another outstanding feat of management to keep Huddersfield Town in the Premier League last term, battling against sides with much richer resources to show grit and resilience to stay up, safety assured with outstanding draws at newly-crowned champions Manchester City and at Chelsea at the campaign's climax.
Life has been tougher this season, Wagner's side undermined by a lack of a goalscorer and eight points from safety after only two wins from 22 games. Relegation looks inevitable.
Wagner, however, will be remembered with great affection whatever the outcome this season as the man who brought the fairytale to Huddersfield Town and whose effervescent personality galvanised the club and the town during his time in west Yorkshire.