Wallop

Wallops are enemies introduced in Super Mario 3D Land. They are a Whomp sub-species shaped like a wall with black eyes and yellow pupils, with mouths and feet.

Super Mario 3D Land
Wallops make their first appearance in Super Mario 3D Land, where they are found in many places of various themes. They block Mario's way, walking in front of him and taking the same directions Mario goes, stopping him from getting past it. Wallops can also jump whenever Mario jumps and then slam the ground. After jumping, there will be a few seconds in which the Wallop will recover, giving Mario or Luigi a chance to pass by it. When the player is a certain distance away from or behind a Wallop, they will be in a state of dormancy, in which their pupils are no longer lit and their feet have retreated into their bodies, until the player is in front of them. Mario or Luigi can destroy them by standing below them when they jump as Statue Mario or Statue Luigi, or turning into a statue above them. They make their first appearance in World 3-1; they also appear in World 6-4, World 8-6, Special 3-5, Special 6-1, Special 8-4, and Special 8-Crown.

Super Mario 3D World
Although Wallops don't appear in Super Mario 3D World, a sub-species called Walleyes act similar by blocking Mario's way.

Trivia

 * Wallops' mouths are identical to those of Rhomps.
 * The move Wallops use when they slam the ground strongly resembles a Ground Pound.
 * Wallops are very similar to Blocky from the Kirby series.
 * Like Whomps, Wallops seem to be inspired by the Japanese, mythological creature nurikabe. Nurikabes block the path of travelers, just like Wallops do.
 * The name Wallop is also a pun on "wall", due to how they look and behave like walls all the time, and the term, "wallop", which means to make a loud crushing noise, or a large attack or beating.
 * By running into a direction and immediately turning the other way, Mario or Luigi can get through the Wallop without jumping.