President Koopa

"Here's what's logical to me... if you do not return with the plumbers and the rock... I shall personally kill you."

- President Koopa

President Koopa is a former military leader under King Bowser, until he revolted and took control of Dinohattan from him. He later plotted a full-scale assault and takeover of the human dimension, which he would achieve by reuniting and merging the two dimensions into one by using Princess Daisy to insert a meteorite shard back into its proper place. He is the primary antagonist of the Super Mario Bros. film.

History
Sixty-five million years ago, a meteorite crashed onto earth, somehow isolating a population of dinosaurs in a dimension parallel to Earth, where some eventually evolved into a human form. Koopa is one such humanoid dinosaur, having descended from Tyrannosaurus rex.

Originally serving as a top general, Koopa eventually seized control of Dinohatten from Daisy's father, whom he turned into fungus, with plans to use a shard of the meteorite to reunite the dimensions and allow him to take over Earth as well. However, Daisy's mother manages to take the princess and the shard through a portal to Earth, leaving them at the entrance to a cathedral before trying to return to Dinohatten, only to be captured by Koopa. Earlier, he killed the Portal-Keeper as part of his coup d'état, and now demands the meteorite shard from her. In the ensuing struggle, however, Koopa accidentally knocks over a support beam and the tunnel collapses, crushing Daisy's mother and blocking off the portal.

Several years later, when the portal is finally reopened, Koopa assigns his cousins Iggy and Spike, who are also his minions, to retrieve Princess Daisy so he can use the meteorite shard she carries for his master plan. However, his bumbling cousins continuously deliver him the wrong girls, until finally succeeding in kidnapping Daisy. They barge into a mud bath shared by Koopa and his lover Lena (who are discussing how much better Earth is compared to their barren dimension) to announce the good news, however it turns out that they lost the shard to Mario and Luigi in the process of capturing Daisy.

Later, after Mario and Luigi are arrested, they are taken to see their lawyer, who is actually Koopa under an alias. He tries to trick the brothers into handing over the necklace, which has the shard on it and which they don't have anymore, eventually reaching the point where he physically assaults the brothers and orders them and Toad to be de-evolved. In the de-evolution chamber, Koopa witnesses as Toad is turned from a human like state to a Goomba, a strong, large, and stupid being loyal to Koopa. He then orders the brothers to tell him where the necklace is, or face de-evolution. However, the brothers escape, pushing Koopa into the de-evolution device, defeating all of his minions, and setting the machine for the Jurassic period. While the de-evolution ends prematurely and Koopa remains in his human-like form, his eye briefly becoming more reptilian hints that he had in fact been affected by the machine.

Iggy and Spike later break in on another of Koopa and Lena's mud baths, reporting that Mario and Luigi are in the Koopahari Desert. Koopa orders Lena to bring him Daisy, and has Iggy and Spike taken to the de-evolution chamber. However, instead of de-evolving them, Koopa has his cousins evolved, which results in the pair becoming smarter. He then orders the pair to capture Mario and Luigi and retrieve the shard or be killed.

Koopa is discussing training his Goombas with the de-evolution gun when Lena arrives, telling him that Daisy is ready. He is then finally introduced to Daisy, who is in another room with Yoshi, a Velociraptor-like creature. He surprises Daisy by entering the room and telling her Yoshi is a dinosaur. Ignoring her pleas for the whereabouts of her father, Koopa tells her that she also descended from dinosaurs, and, afterward, his head begins to show dinosaur-like traits. A frightened Daisy then runs away, but is caught by a Goomba, whom Koopa demands to take Daisy away.

At another point, he enters Devo 4, the holding chamber for Daisy's father, where he engages in small-talk with the fungus. He eventually states that his rebellion will have been in vain after the dimensions have been united.

Lena later enters Koopa's quarters, secretly possessing the meteorite shard, with Iggy and Spike as her prisoners. She convinces Koopa that they were now against him, and he orders them to be killed. He then walks off with Lena, who tries to reveal that she has the shard, only to be ignored. She bemoans the fact that Koopa only cares about Daisy now, while he states that he only cares for the future of their species and leaves, whereupon Lena decides to take action on her own.

Koopa is later told by the police chief that the army Is ready for the invasion of earth. Alarmed by this, Koopa demands to know who gave the order, to which the chief states that he did, according to Lena. Koopa then figures out that she has the shard, and demands her arrest. He, along with a Goomba entourage, later run into Luigi and Daisy and capture the duo. Afterward, he orders the preparation for the invasion of earth. Eventually, the police chief captures Lena and delivers the shard to Koopa, and he then orders to prepare for the invasion.

Outside, Koopa and a small group of Goombas are distracted as Mario, as well as the missing girls from Brooklyn, fly out of a ventilation shaft on a mattress, allowing Luigi and Daisy to rejoin Mario. However, Koopa then approaches the brothers with a flamethrower, declaring he had won, and gives several commands through a communicator. The distracted Koopa does not notice Luigi grab a Banzai Bill from a local shop, which Mario loads into a Thwomp Stomper and activates it. The stomper knocks Koopa into an empty vat above streets. Mario, using some fungus as a vine, leaps onto the bottom of the vat, climbs on top of it, and hits Koopa, knocking the shard out of his teeth. Not being able to locate the shard, Mario is able to trick Koopa into thinking he has it.

They continue the fight on a catwalk, Mario pulling out the Bob-omb the brothers retrieved earlier and winds it, though the bomb falls through a hole. Unaware that the Bob-omb is still on its trek, the two dimensions begin merging before their eyes. Mario, Koopa, and his legion of Goombas appear at the excavation site after Koopa's tower merges with the World Trade Center. Casting aside the flamethrower, which no longer functions, Koopa takes a de-evolution gun from a Goomba and fires at Mario, though he dodges the blast, which accidentally hits Anthony Scapelli, a business owner, and turns him into a monkey. He tries firing at him again, but Mario pulls out a mushroom the brothers found earlier to absorb the blast. The mushroom starts to grow, eventually becoming really large, and Mario uses it to attack Koopa, knocking the gun out of his hand.

Thanks to the efforts of Luigi and Daisy, the dimensions are split again, and Mario is joined by Luigi, who hands him a de-evolution gun. The brothers then fire the guns at him, just as the Bob-omb arrives right beneath Koopa and explodes, sending him flying into the empty vat. After a moment of silence, he emerges from the vat, having de-evolved into a tyrannosaurus. The brothers then continuosly blast Koopa again until he finally devolves into primordial ooze.