Former colleagues and team-mates – and opponents in the football world – joined fans in reaction to the news which follows defeat to Ross County and Celtic dropping 18 points off Premiership leaders Rangers.
“I hope he can get a bit of sanity back in his life, go and relax with his family. That’s the one thing that Neil needs and probably wants, so that’s the important thing and get away from the insane pressure of being an Old Firm manager.
“In terms of the decision itself, not surprised. I think the way the season has gone for Celtic this year, it has effectively been one disaster after another.
“There are a lot of people responsible for that. Neil being the manager is obviously one of them. The people above him and the players have to shoulder a lot of the responsibility.
“Everyone at Celtic wanted the magical figure of ten, for some time now – I always felt there was a, not from Neil I may add, an element of arrogance coming from within Celtic. They just thought it was a formality.” (Talksport)
"Neil Lennon can be proud of his achievements both as a player,coach and manager of Celtic. I’m not surprised he has resigned but feel it’s the best outcome for Celtic,the club now need to move quickly and get a new manager and his staff in for the challenges ahead.” (Twitter)
"Neil Lennon had to go. I know this season has been a disaster but I hope after the anger settles down about this season that people respect that Neil has been a great servant to Celtic both as a player and manager.” (Twitter)
In his Daily Record column he added: “The bottom line is that is Celtic have regressed this season under Neil. Badly.
“They have regressed and there has been so many things done wrong and so many bad decisions that it became impossible to defend him anymore even if you were his biggest fan.
“Celtic have been shocking this season. He had a go at people who called it a disaster season, but what else would you call it?” (Daily Record)