Lakithunder

Lakithunder is the World 7 boss in New Super Mario Bros. He is a Lakitu with sunglasses and rides a dark cloud; he is a member of the Koopa Troop. As the name implies, he can shoot lightning directly under him, and also throw Spinies like the other Lakitus. Mario must Jump on Lakithunder's head three times, when he swoops down low, to defeat him. Lakithunder does not need to be defeated to complete the game, as World 7 is optional.

Trivia

 * Lakithunder is likely the one who had attacked Peach's Castle in the game's intro, because a dark cloud is shown attacking the castle.