So that's 13 down, more than half the league and this one more bizarre than most. Oldham are 8th and one point off a play-off place!
44 year old Sheridan has been in charge for almost three years.
A club statement confirmed the decision was made after talks between Sheridan and managing director Simon Corney on Sunday morning.
His departure comes after reports last week that players brawled during a club night out at Belle Vue greyhound track. Newspapers also claimed Sheridan was involved in the incident, though he said the reports were exaggerated.
Corney told BBC Radio Manchester that Sheridan's departure had nothing to do with the incident at Belle Vue: "The timing is unfortunate because people will draw conclusions but they are wrong in this instance. If I am honest, one or two players have let him down recently (not ex-Captain Kev I hope) and they need to look at themselves because to a degree they have cost the manager his job."
The club announced on Thursday that one player had been fined two weeks wages with two others warned about their future conduct.
'Big Joe' as he is affectionately known by Latics fans, will take charge with immediate effect.
Royle, 59, is arguably the most succesful manager in Oldham's history guiding them to a Littlewoods Cup final and FA Cup semi-final as well as three seasons in the top divisions.
He left in 1994 to join Everton - helping lift the FA Cup - before moving to Manchester City where he guided the Blues to back-to-back promotions.
He left his last managerial post at Ipswich Town in May 2006.
Royle will be officially unveiled at a press conference at Boundary Park tomorrow.