Ludwig Von Koopa

Ludwig Von Koopa (or Kooky von Koopa) is the oldest and supposed leader of the seven Koopalings, and a recurring antagonist in the Super Mario Bros series. He is traditionally the seventh and final Koopaling fought in most Mario games, with a few exceptions such as Super Mario World or Mario & Luigi: Superstar Saga.

Super Mario Bros. 3
Ludwig is the seventh Koopaling to be fought. Like his brother Roy, he causes an earthquake when he lands. He must be jumped on three times to defeat him. Ludwig turned the king of Pipe Land into a Piranha Plant, but was defeated by Mario and Luigi in his airship, and ran off. In the SNES game Super Mario All Stars, which had remakes of all 3 NES games and lost levels of Super Mario Brothers, he turns the Pipe Land king into a dinosaur reminiscent of Yoshi.

Super Mario World
Ludwig is the fourth Koopaling to be fought, at the Twin Bridges. His fighting style is different from those of the other koopalings, but like all of them except Larry and Iggy, he must be jumped on three times to defeat him. He is fought in the biggest battle arena in the game, resembling a bridge above lava. Once defeated, he spirals into the distance and explodes in a puff of smoke.

Mario & Luigi: Superstar Saga
Like previously destroyed members of the Koopa Troop, Ludwig returned in another game. This time, however, he did not work for his father, Bowser, but the one possessing him: Cackletta. Like in Super Mario World, he was the fourth to fight Mario and Luigi, and was defeated. Afterwards he apparently dies and disintegrates like the other defeated enemies.

Super Princess Peach
Ludwig was going to appear in Super Princess Peach (as were his siblings, except Bowser Jr.), but the decision was dropped, though after sprites were created for all of them.

New Super Mario Bros. Wii
For the first time, the Koopalings and Bowser Jr. appear together in a game. Like in Super Mario Bros. 3, Ludwig is the last Koopaling to be fought. Kamek uses his magic to make three platforms in the room rise, to which Ludwig's shell attack is not a threat (if Mario can jump to a different platform), Mario, Luigi, or the Toads will fall to their deaths if they fall off the platforms. It is Ludwig who falls over the edge when Mario jumps on him three times. Ironically, he survived what should have been a fatal fall, as he is seen in the ending sequence with Bowser, Bowser Jr., and the other Koopalings, though Bowser's castle falls on top of all of them.

New Super Mario Bros. 2
Ludwig is the main antagonist of New Super Mario Bros. 2 alongside his fellow Koopalings and Bowser and is once again the final Koopaling to be fought (though Larry and Lemmy can optionally be fought after him). Ludwig is the apparent ringleader behind the kidnapping of Princess Peach, evident by the fact he controls the Koopa Clown Car throughout the game. When fought, he flutter jumps on chains hanging on the ceiling and fires multiple magical fireballs at Mario, who must use cannons to knock Ludwig off the chain. He and the Koopalings later fall into a pool of lava after accidentally being knocked over by Bowser, who the Koopalings magically enlarged, but survive. They are later seen rescuing Bowser, only to lose control of the Clown Car due to Bowser's weight and crash land, with Ludwig lying on the ground sulking.

Mario Kart 8
Ludwig as well as all of the other Koopalings made their first appearance as playable characters in Mario Kart 8. He and Iggy are the only two Koopalings to be in the upper medium class. He is voiced by David J. Goldfarb in this game, who gives Ludwig a higher pitched voice.

Super Smash Bros. for Wii U and 3DS
Ludwig has been confirmed to be an alternate costume for Bowser Jr. in the video games; Super Smash Bros. for Wii U and Super Smash Bros. for Nintendo 3DS.

Trivia

 * Ludwig's name and hairstyle are derived from the composer Ludwig van Beethoven. However, according to Nintendo, the Koopalings (including Ludwig) designs were based on Super Mario Bros. 3's design team.
 * It is hinted that Ludwig and Bowser Jr. have a slight brother rivalry because of their undying loyalty to their father, they sometimes fight and compete over his love, attention and favour.