Skewer

Skewers (also known as Spikes and Spike Pillars) are grey, blue, or green pillars with spikes on them. First appearing in Super Mario World, they can either power-down Mario or crush him for an instant life loss. In later titles, however, the Skewers can only power-down Mario.

Super Mario World
Originally appearing as light grey stone pillars in fortresses and castles, the Skewers are all vertical in Super Mario World, moving up and down blocking the path. There are usually several of them in a row which have to be timed. There were also some yellow miniature ones without spikes (resembling pencils) in Chocolate Fortress and #7 Larry's Castle.

New Super Mario Bros.
The Skewers returned (including some horizontal ones now) in New Super Mario Bros. (now metallic military green with yellow spikes). They appear only in and.

New Super Mario Bros. Wii
Skewers, referred to as pistons in the Prima game guide, make a comeback in New Super Mario Bros. Wii (now steel grey with gold spikes), the latter of which also features a very long and extremely fast Skewer that runs along the floor for the length of a long room in, and very large vertical ones in and. The sound they make is that of a large sliding gate slamming.

Super Mario 3D Land
Skewers from New Super Mario Bros. Wii make a return in the Nintendo 3DS game, Super Mario 3D Land, marking their first appearance in a 3D Mario game; they are no longer in castles, instead appearing on airships. They cannot be destroyed, even while invincible; as Statue Mario or Invincible Mario (including White Tanooki Mario), they are like walls if run into with these powers.

New Super Mario Bros. 2
In New Super Mario Bros. 2, Skewers make a reappearance. However, unlike past New Super Mario Bros. installments, they are blue, and they appear only in one course,, which is water-filled course, and only horizontal Skewers are featured.

New Super Mario Bros. U
Skewers also appear in New Super Mario Bros. U, where they are found only in Giant Skewer Tower. All the Skewers are horizontal and are once again dark grey with gold spikes as in New Super Mario Bros. Wii, and their lengths vary. The Skewers also appear in the New Super Luigi U course, Shish-Kebab Tower, but they move at faster rates than in New Super Mario Bros. U.

Super Mario Maker
Skewers return in Super Mario Maker as an addition in a software update that was released on March 9, 2016. They function identically to their previous iterations, activating every few seconds, but with some differences. Their points have been flattened, they come with a base that they shoot out of, and have a maximum length of 13 blocks long, plus the base, unless they hit terrain. Skewers can be used by shaking the Thwomps; however, they can't be enlarged with Super Mushrooms.

Super Mario World television series
The regular Skewers from the game also appeared in the Super Mario World cartoon, in the episode "Mama Luigi".

Mario Party: Island Tour
These obstacles also appear in the minigame from Mario Party: Island Tour, Kabob and Weave, where players must simply avoid them.

Mario Party 10
Skewers reappear in Mario Party 10 in the minigame Skewer Scurry, and appear as an obstacle in Chaos Castle on the unlucky spaces to take away mini stars from the player.

Wario Land: Shake It!
In Wario Land: Shake It!, Skewers are featured only in underwater levels. If Wario inside his Subwarine comes in contact with these, the Subwarine will take damage reducing Wario's heart health to half.

Donkey Kong Country Returns
Donkey Kong Country Returns and Donkey Kong Country Returns 3D also contain some Skewer-like obstacles in the temple level, Jagged Jewels.

Super Smash Bros. for Nintendo 3DS / Wii U
Skewers from Super Mario 3D Land also appear in a stage based on a level from said game in Super Smash Bros. for Nintendo 3DS, where they rise from the water and can destroy part of the stage's platforms (which resemble those of World 1-4 from Super Mario 3D Land), as well as hitting any players who touch them.

Mario & Luigi: Paper Jam
Skewers make a minor appearance in Mario & Luigi: Paper Jam, where they are found in Neo Bowser Castle in the lava pit.

Trivia

 * If Shell Mario ducks in a Skewer's path, he won't get powered down.