Ogremon

Ogremon is an Evil Digimon (Oni in the original) and a bounty hunter by reputation, earning the nick name "Digimon Hunter". His arch-nemesis is Leomon and has counterparts in Fugamon and Hyogamon. He carries a bone club that is said to be a femur of a slain SkullGreymon.

Digimon Adventure
Ogremon was the only Digimon who willingly came to serve Devimon, under the promise to kill Leomon once Devimon no longer needed him.

But prior to the final battle, Devimon grabbed Ogremon by the throat and transformed him into a mass of Black Gears that he assimilated, along with all the other Black Gears on File Island, into his body so he could have the power to destroy the DigiDestined. He tried to attack Angemon, but Angemon hit him with his staff, sending him flying out of Devimon's body and into the forest. After the battle, he wanted revenge for Devimon's death, but was scared off by Leomon.

Upon Devimon's destruction at the hands of Angemon, Ogremon escaped. He was eventually forced to battle the forces of the Dark Masters. As it turned out, Ogremon was never actually evil, he only wanted to fight Leomon and no one else. After getting injured by some Woodmon, Ogremon allied with the two DigiDestined Mimi and Joe after their split with the other DigiDestined.

He wanted to help against MetalEtemon, but Mimi stopped him because he was still too badly injured and this led to MetalEtemon trying to blast Mimi and SaberLeomon taking the attack for her. Before Leomon died of his wounds, the two old enemies made peace. After Leomon's death, Ogremon decided to help the kids in any way he could for his rival's sake.

When Mimi showed up to help against Piedmon, Ogremon was part of her army and helped defeat the Vilemon, leaving with the other digimon once Piedmon was destroyed. Following the defeat of the Dark Masters and Apocalymon, Ogremon left to be on his own once more to await the day that he and Leomon could resume their rivalry.

Ogremon would later be referenced in the first episode of Digimon Adventure 02, when T.K. and Kari commented that their teacher looked like him. He would also appear in the epilogue of the final episode, where Joe was teaching his son how to treat Digimon by using Ogremon as an example (referencing his treating of Ogremon for his injury in Digimon Adventure 01).