Neil Harris has stepped down as manager of Championship club Millwall after more than four years in charge.
The Lions are winless in their past seven league matches and are 18th - five points above the relegation zone.
Harris, 42, was appointed as boss in April 2015 following a six-week spell in caretaker charge.
His assistant David Livermore has also departed The Den and Adam Barrett has been placed in temporary charge ahead of the visit of Leeds on Saturday.
"I would like to place on record my sincere gratitude to Neil for all of his hard work, commitment, determination and inarguable success," chairman John Berylson told the club website.
"Neil's achievements ensure that he is listed alongside some of the club's greatest-ever managers, furthering his legendary standing at Millwall.
"He has laid tremendous foundations from which the club can continue to build on in the months and years ahead.
"Neil's name is synonymous with Millwall and he has always had the very best interests of the club at heart, managing with great pride, honour and integrity, and he departs with the best wishes of everyone connected with the Lions."
Under the management of Harris, who scored 138 goals over two separate spells with Millwall as a player, the Lions reached the FA Cup quarter-finals twice, in 2017 and 2019.
He remains the club's all-time top goalscorer, despite being diagnosed with cancer when he was just 23.
He guided the club to promotion back to the second tier in 2017, after reaching the League One play-off final for a second consecutive season.