Managmement Today [UK] gives advice on how to deal with BIG EGOS:

If you are their boss

This is your key responsibility – so don’t shirk it, even if they are your star performer. It is rare in business today that one person can do everything; you need the whole team to succeed. Tackle them directly, and in private. The key message is ‘You are great, and you could be even better’.  Focus on the fact that this type of behaviour is hindering their promotion prospects.

If you are their colleague

Remember to have the right mindset – you are not trying to put them down, you are trying to help them to be more effective. Tackle them in private, and if you can get another colleague to come along too then that helps. You need to show them that it’s not just ‘you versus them’ but that there is a wider consensus within the team that things need to change. Focus on giving them alternative behaviour strategies.

If you are an underling

This isn’t your responsibility – but you can transform the working environment and your own reputation positively if you choose to tackle the big egos – remember David and Goliath. Strange as it may seem, it’s best to tackle them in a very public forum: our culture does not allow egotists to crush the little people, so you will get back up from others. Focus on how their behaviour is demoralising you and others – so the emphasis is not on them, but the effect it has on you. Try and have a word with one of their work colleagues beforehand so you know you have an instant ally.

We all want great strikers on our team who can get the ball in the back of the net at the critical time. We all accept that with some of these skills is bound to come a good dollop of personal ego, and we can cope with it most of the time. We also all have a duty to stand up to these egos when they get too big for their boots

– Christopher Barrat is a motivational speaker and communications expert to those in the public eye. He can be contacted at www.greystone.co.uk  read the full article here