Lakitu's Cloud

Lakitu's Cloud (originally known as Jugem's Cloud) is the cloud with the smiley face on it that Lakitu usually inhabits.

In Super Mario Bros. 3, Lakitu's Cloud is used to skip a level you dislike.

In Super Mario World, Super Mario World 2: Yoshi's Island, Super Mario 64, and New Super Mario Bros., after taking out the Lakitu inhabiting it (if there is one), you can jump on Lakitu's Cloud to reach places that you can nomally not get to.