|“||You annoying little maggots!||„|
|~ MadLeomon to Shoutmon|
MadLeomon is an unknown level Digimon that resembles a zombie/lion hybrid creature, a parody version of Leomon except he has spikes on his shoulders like Ogremon's, dark red eyes with black irises, purple claws, red teeth, and bones sticking out from his chest. Like almost every other antagonists in Digimon Fusion, MadLeomon can fuse with other Digimon to make himself stronger. He dislikes humans who come to the Digital World.
As Armed MadLeomon
In this form, MadLeomon absorbed an army of Mammothmon, Troopmon, and Chikurimon. His entire body is covered in armor wrapped in chains, and has a chainsaw for his right hand.
As MadLeomon Orochi Mode
In this form, MadLeomon absorbed an Orochimon and has his body. MadLeomon's mane changes from black to yellow, his arms and legs are snake, has two snakes that come out of his back, snake-like shoulder armor, and a snake's rattle on his tail.
As MadLeomon Final Mode
In this form, MadLeomon absorbs three Apemon. MadLeomon's mane becomes blood red, his spikes are longer and sharper, wears a yellow loincloth, and appears to be more muscular.
Originally, MadLeomon was Leomon, the guardian of the Forest Zone until he was corrupted by Bagramon's evil and became a member of the Bagra Army. MadLeomon first appeared when Mikey and the others arrived in the Digital World, attempting to kill them when they are saved by Ballistamon, Starmon, and the Pickmons with Shout having them in defeating MadLeomon's forces. In retaliation, MadLeomon absorbs his followers to assume his Armed Mode and nearly killed the Digimon when Mikey uses his Fusion Loader to give Shoutmon the edge to defeat MadLeomon with the Star Sword. Despite his reluctance to run, MadLeomon is forcefully recalled by Tactimon.
Later on, refusing to let humans run rampant in his domain, MadLeomon decides to destroy the Village of Light using an Orochimon before using it to kill Mikey and his friends instead. But when he sees that Orochimon was being overwhelmed by Shoutmon, MadLeomon Digifuses with the eight-headed serpent to assume his Orochi Mode form before being defeated by Shoutmon X2. Forced to retreat, MadLeomon is given one more chance by Tactimon to wipe out their enemies.
Using a Drimogemon to create giant bamboo shoots, MadLeomon sends army of Apemon to attack the group before absorbing them to enter his Final Mode. During the battle, the Starmons fused into a sword, allowing Jeremy (who was trapped on top of a spike wall) to toss it into the ground, where it struck Drimogemon on the head, killing him and the bamboo shoots started to fade away. Though defeated by Shoutmon X2 and Dorulumon, MadLeomon decides to show himself his ultimate power so he can destroy the resistence. Shoutmon Digifused into Shoutmon X4 (as X3) for the first time and MadLeomon attempts to crush him, but Shoutmon X4 (as X3) tosses MadLeomon into the sky and destroyed him with his Varooma Boomerang attack. With MadLeomon defeated, Mikey receives his first Code Crown.
After Mikey acquire the last Code Crown, during a fight with Grademon, he ended up wishing he could do something to save Grademon from his corruption. When that happened all of the evil Digimon that were defeated by the Fusion Fighters were revived and their evil were purged. One of them was MadLeomon who was revived and reverted back to his original form, Leomon, adding Mikey during the final battle with DarknessBagramon.