Lucy is a blue-and-purple firefly. In The Good Night Show, Lucy introduced the shows that came between the block. She was also featured in games, such as "Lucy Light the Way". In this game, viewers were shown parts of a picture (as though they were illuminated by a firefly's light) and then guessed what the picture represented.

Lucy was originally depicted as a glowing finger puppet, but she later became a CGI character, then becoming an animated character in the spin-off Nina's World.