His focus on stem cell research, on getting himself better as an example for other people, was very inspirational.

I think we have lost a very brave and courageous and dedicated individual.

Christopher and I saw a lot of each other on the Superman set, and we'd have lunch together and saw each other socially.

He was very like how he comes across on film - very strong, very brave, very forthright and very generous-spirited.

He was earnest and dedicated to making Superman so that he would not disappoint children or adults who had grown up with the Superman comics.

Christopher really wanted to personify and become the character of Superman and I think he did that wonderfully.

He was also very inspirational in the way he behaved after his accident.

The reason he himself kept up such an incredibly brave front was to show that life does go on.

I'm sure he must have felt deep, deep anguish and physical pain after his accident, but he had an enormous inner personal strength which meant he didn't show his suffering a lot.

That is true bravery.

Family support

And he was clearly enormously supported by his family and his wife, who must have been equally brave.

Christopher's stem cell campaigning was tireless and not just for himself, but for other people who have been struck down or disabled.

He alerted the world to stem cell research and he has taught the ordinary man on the street more about it than they ever knew.

I think Christopher would want to be remembered for both his acting and his campaigning and quite rightly so.

They were both great achievements. His life was a great achievement.