A man who cannot open his eyes without destroying whatever is in front of him, and who is therefore extremely careful about everything.
Cyclops is the most thankless part in these films. He is the field leader, the rule follower and the one who is correct about the risk, and the story is usually about somebody who is not. James Marsden played him for three films and was written out at the start of the third, which is one of the reasons that film is remembered the way it is.
Tye Sheridan’s version gets the better introduction: a teenager whose power arrives with no warning at all, in a school corridor, and cannot be turned off again.