Girder

Girders are platforms found in a handful of games.

Donkey Kong / Donkey Kong (Game Boy)
Girders first appear in Donkey Kong and its remake, appearing in practically every stage, most notably in 25m. In both games, they act essentially as a semi-solid platform that Mario can walk on.

Mario vs. Donkey Kong series
Girders appear in every single Mario vs. Donkey Kong game. In Mario vs. Donkey Kong, they act as a semi-solid platform much like Donkey Kong. They also appear in all subsequent games and behave in the same manner for the Minis. Additionally, a special type of Girder called a Red Girder can be drawn from red blocks with screws in them.

Donkey Kong Country Returns
In Donkey Kong Country Returns, girders are the primary floor in the Factory world. In the background for the Factory's first level, Foggy Fumes, girders arranged in the zig-zagged 25m layout can be seen at one point. This pattern also commonly appears on wall reliefs throughout the temple-themed levels, along with other depictions of Donkey Kong arcade graphics.

Super Mario Odyssey
Girders appear in Super Mario Odyssey, where they are found as common platforms found throughout the Metro Kingdom. They do not act as semi-solid platforms in this game, but items such as Coins and Power Moons can be found inside some of them.

Other appearances and references
In the manual for Donkey Kong 64, Cranky Kong hopes that a level design he submitted, "Girder Grapple," made it into the game, referencing him being the original Donkey Kong from the arcade game. While this level doesn't appear, the original game can be played in an arcade cabinet found in Frantic Factory.