A chicken little is a person who thinks everything is going to be bad.

Hi, Luis! "Chicken Little" is the name of a cartoon character (a chicken) in a children's story. Chicken Little runs around shouting, "The Sky is Falling, The Sky is Falling", whenever anything--no matter how insignificant, goes wrong. For example, if the sky is cloudy, then Chicken Little would probably be very worried and say, "Oh, no--a big storm is coming and everything will be destroyed."