Big Koopa Troopa

Big Koopa Troopas, or Big Koopas, originally known as Giant Koopas, are gigantic versions of normal Koopa Troopas that appear throughout the Mario franchise.

Super Mario Bros.: Peach-hime Kyushutsu Dai Sakusen!
In the 1986 anime Super Mario Bros.: Peach-hime Kyushutsu Dai Sakusen!, an unusually large green Koopa Troopa appears during a walking montage scene. It looks curiously at a passing Mario, Luigi, and Kibidango before jumping on them. However, Mario uses the power of the mushroom he had recently acquired to push it off of them by growing even larger than it. The next shot of it shows it apparently regressed to normal size, staring at the super-sized Mario next to a similarly shocked Buzzy Beetle.

Super Mario Bros. 3
Giant Koopas appear in Super Mario Bros. 3 and reside only on Giant Land (along with other gigantic creatures like Grand Goombas and Piranhacus Giganticus). Mario and Luigi have a harder time avoiding these Koopas because of their increased size. Despite this, if the plumbers stomp on a Giant Koopa, it hides inside its green or red shell, just like an average-sized Koopa Troopa does when it feels threatened. Once inside, the plumbers can kick their shells away. In the Nintendo Power Strategy Guide, they are split between Green Gargantua Koopa Troopas and Red Giant Koopa Troopas.

Super Mario 64
In Super Mario 64, a single Giant Koopa known as Koopa the Quick appears in Bob-omb Battlefield and Tiny-Huge Island as a friendly racing rival to Mario.

Super Mario Galaxy 2
Giant Koopas reappear in Super Mario Galaxy 2 in the Supermassive Galaxy. Only three are found patrolling a solitary planetoid where they attempt to flatten Mario if he gets in their way. They can only be defeated with a Spin Drill by drilling into their belly from the opposite side of the planet. If Mario performs a Long Jump on a Giant Koopa so that he catches up with it each time, he can get 1-UPs for every consecutive time he stomps onto it after seven initial consecutive jumps, allowing maximum lives to be gained. Once one is defeated, it drops one coin.

New Super Mario Bros. U / New Super Luigi U
Big Koopa Troopas appear in New Super Mario Bros. U, and are common enemies in Jungle of the Giants. The player is no longer able to carry their shells in this game. Additionally, their shells are able to break through normal-sized Brick Blocks without bouncing off. Unlike previous appearances, the Big Koopa Troopa is bipedal and wearing shoes.

Big Koopa Troopas also appear in New Super Luigi U, in Giant Swing-Along.

Super Mario Maker / Super Mario Maker for Nintendo 3DS / Super Mario Maker 2
Big Koopa Troopas come in green and red varieties in Super Mario Maker, Super Mario Maker for Nintendo 3DS, and Super Mario Maker 2. In the Course Maker, after the player drags a Super Mushroom onto a standard Koopa Troopa, the enemy grows in size. Just as in New Super Mario Bros. U, its shell cannot be carried, and this applies even when playing in Super Mario Bros. 3 style, whereas in the said game, the player could transport the shells of Big Koopa Troopas. Big Koopa Troopas now have the ability to break Hard Blocks.

Super Mario World 2: Yoshi's Island
In Super Mario World 2: Yoshi's Island, a regular Koopa Troopa named Hookbill is transformed by Kamek into a giant-sized Koopa as a boss of World 4.

Paper Mario
In Paper Mario, a greedy and nearsighted Giant Koopa named Kent C. Koopa appears as an optional boss in the game. Notably, he has taught the Koopa Bros. how to fight, and is known as a 'bully,' who refuses to let Mario pass unless Mario pays 100 coins. If Mario disobeys him, Mario and his partners must fight Kent C. Koopa to get him to return to Koopa Village.

Mario & Luigi: Superstar Saga + Bowser's Minions
Big Koopa Troopas appear as obstacles in Mario & Luigi: Superstar Saga + Bowser's Minions, replacing the Nokottasu from the original game. They stand in the middle of various paths in the game, and only Mario's Firebrand Bros. Dash technique can knock them over and make them move. A non-obstructive one also appears in a house in Beanbean Castle Town.