Keane On Signing: "It is a great move for me. It was important I took my time over the last three or four weeks.
"It has been a strange few weeks but this is a great move for me.
"There has been a lot of speculation in recent weeks over where I was going but I gave every club a chance and I spoke to a lot of managers.
"I spoke to Madrid up as far as Tuesday and Madrid explained to me they were waiting a week or so.
"That was fair enough but it was about time I made a decision.
"Having spoken to the manager I thought this is the club for me.
"I have met one or two of the players and feel this is where I belong."
Keane On Himself: "They are getting a pretty decent player. A lot has been said about my injuries and age but I have a lot to offer and I will surprise a few people.
"I have been a midfielder professionally for the last 15 or 16 years. If you are challenging for trophies, then you always need a big squad.
"The players at Celtic have done very well so I am under no illusions that I will walk into the team.
"I have never taken my place in the team for granted. I aim to train hard and give the manager a problem.
"At my previous club when they bought a few midfielders, I saw it as a challenge so hopefully those here will do the same."
Keane On Manchester United: "There's been a lot of nonsense written about what I was supposed to have said.
"I want to push my team-mates hard, but people were up for that up until a few months ago."
"I haven't come up here on an ego trip or to unwind. I'm here to win matches.
"I'm a team player despite a lot of reports. I feel I can help the club move on to the next level, which is winning trophies.
"That's what I'm in the game for. I'm not necessarily in the game to be popular.
"I like pushing myself and the people around me hard but there seems to be a fault with that in the modern day."
"I was contracted to Manchester United and I was convinced up to last year I would end my career there - but things change."
"I had a great time at Manchester United - they are a fantastic club.
"If you had told me again I would spend 10-and-a-half years there, I would be lucky.
"The manager was great to me there but our relationship came to an end.
"It was very amicable and we shook hands and wished each other well.
"United will go on and life will go on and Roy Keane will go on.
"I wish everyone well at United, they are a fantastic club."
Keane On Money: "Football has been good to me. If it was about money, I wouldn't have gone to Manchester United when I left Nottingham Forest.
"I could have left United many times over the years when my contract expired and they will tell you that.
"But if you concentrate on your football and following your gut feeling then the rest will follow.
"Money comes into the package and I leave that to my solicitor to negotiate but as far as I'm concerned it's about what is the best for me in terms of football.
"There is a new mentality in terms of money being the priority for some players but it never has been for me and believe me it never will be."
Keane On Captaincy: "The captaincy is a bonus. I'm all about the team. The team always comes first and the captaincy doesn't bother me one bit."
Gordon Strachan On Keane: "Roy and I met for two hours in London two weeks ago and he is a clever man.
"I had to find out if Roy was interested in playing for Celtic. That's why we met. I told him where I was going and he said he was up for it."
"If you think we've got a bunch of shrinking violets, don't tell Sutton, Lennon and Thompson because they are aggressive as anyone in training and demanding.
"But to add to that is fantastic. It was too good a chance to miss out on one of the world's great competitors."
Peter Lawell On Keane: "A great player has joined a great club. We are absolutely delighted - the board, the management and the players.
"We wanted him and eventually got him - total unity across the club, no divisions.
"Dermot Desmond has been a fantastic supporter of this transaction. But in terms of his support that is where it started and ended. There is no financial contribution Dermot will make towards this deal."
Dermot Desmond On Keane: "From the word go it was the manager's decision and the board's decision to go after Roy Keane.
"In fairness to Roy Keane he left a lot of money on lots of tables because of his love for Celtic.
"What swung it for Roy was his love of Celtic and I would hope that he respects Gordon Strachan, respects the team."
Strachan angrily snapped at suggestions he had played no part in Keane's move when the player was unveiled.
"I am very comfortable with Roy, as are other members of the board, so we have no fears that he will be an unsettling influence.
"On the contrary, I think he will harness all the good things that are in Celtic Football Club."