Ipswich boss Keane skippered Manchester United and the Republic of Ireland during a playing career punctuated with controversy.
He had several run-ins with referees and the football authorities, famously walking out on his country on the eve of the World Cup finals in 2002.
Father-of-five Keane admitted: 'We all make mistakes and there's no halo over my head.
Natural born leaders: Former Ireland skipper Keane (left) and Terry
'I'm in no position to comment on anyone's private life and it's very, very easy to kick a man when he's down.
'I'm certainly not going to do that but when you're in the public eye, as I've been for the last 10 to 15 years, you have to be careful.
'You remember the support you receive, like when I was getting hammered years ago for something. I don't know what it was - I must have kicked somebody or it might have been something I said in my book.
'Even one or two of my United team-mates had a few words to say and I certainly wasn't happy with them.
'You remember the people who support you and John Terry probably needs that more than anything else right now.'
SHOWDOWN! Fabio Capello flies in for summit with John Terry as Wayne Bridge prepares to take the field at Hull England boss Fabio Capello will announce on Friday whether Terry will continue to lead his country after news broke he had an affair with the ex-partner of international team-mate Wayne Bridge.
But regardless of Capello's decision Keane doesn't see it impacting on England' s chances in South Africa this summer.
Feeling blue: Terry is still Chelsea skipper
Keane added: 'I don't know how the manager works and I don't know his mindset. There's all this talk about the captain but you don't have to wear the armband to be a captain.
'I think the England captaincy is made out to be a bigger issue than it really is.
'Whether it was Bryan Robson, Alan Shearer or whoever, I always thought it was over the top.
'If England are going to have any chance of winning the World Cup they can't be relying on one captain.
'There are three or four captain types, whether it be Rio Ferdinand, Wayne Rooney or somebody else.
'I think England have a very good chance of winning the World Cup whether John Terry is the captain or not.
'Like a lot of international teams you usually find several club captains in the group anyway.
'Just because you're not wearing the armband does it mean you can't lead people, or battle with them and fight with them? Of course not.'
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