Invincible Mario
Invincible Mario is a form Mario assumes after using a Star. In this state, which only lasts for a few seconds, he is resistant to any enemy. Morever, he is able to defeat them by simply touching them. He is not protected from falling into a pit or dying when time's up, however. Invincible Mario, just like the Star, made his first appearance in Super Mario Bros. Invincibility is depicted by a flashing, and, in later games, also color-changing character. Since this isn't really a transformation, Mario can become invincible and mantain the form he had before, for example, if he's Fire Mario and gets a Star, he becomes invincible, but he's still in Fire form. In the Mario Kart series, every driver could become invincible by collecting and using a Star, allowing him to make other drivers slide by touching them.
In Super Mario Bros. 3, there are some ? blocks that normally contain coins but that contain starmen if Mario is invincible.
