Shan Yu is the main villain from Mulan, and the leader of the Hun army.
Shan Yu is among the most ruthless, and merciless villains ever seen in the Disney universe. He proves that it is not below him to kill his enemies in cold blood to prove his strength. He even makes jokes about it, rhetorically asking his lead archer how many men it takes to deliver a message, to which the archer is seen drawing his bow and commenting "One", and is then implied to have killed one of the spies.
Shan Yu is also supremely confident in both his and his army's strength and superiority, often deliberatly allowing his enemies the advantage in order to prove his might. Such examples include his attack on the Great Wall, where he allowed a lone sentry to light the signal fire, sending word to the Emperor and giving him time to mobilize the Imperial Army. Later, he allows one of the Chinese spies to return to the Forbidden City, smugly telling the spy to inform the Emperor to send his best troops to face the Huns. He also decides to head straight for the mountain pass that would lead him straight to the Forbidden City, knowing full well that the entire Imperial Vanguard is guarding the pass and completly rejecting the option to simply go around the mountains and avoid the enemy army.
Shan Yu is a hardened fighter and a lethal combatant, armed or not as shown where he overpowers Shang in a fight. He possess superhuman strength (perhaps second only to Chen-Po). He can break down a barricaded door with no effort and simply slice a massive pillar to shreds with his sword. He is a skilled tracker and survivalist, being able to deduce a doll delivered to him by his falcon came from a village in a nearby mountainpass where imperial armies awaited him by only a few subtle clues found on the dol (white horse hair from an imperial stallion, black pine which grows in the mountains, and the smell of sulphur from a cannon).
The film's opening scene sees Shan Yu scaling the Great Wall of China and leading the Huns in an invasion of China, setting the tone for the rest of the film. His armies crush the Emperor's soldiers with ease until they get to a mountain pass where they are cut off by Captain Li Shang's troops. Though the Huns vastly outnumbered Shang's troops, Mulan managed to bury them in an avalanche by aiming a rocket at a nearby mountain.
Believed to be dead and defeated, Shan Yu and a group of surviving Huns were able to infiltrate the Emperor's palace and capture him during the victory ceremony. Mulan, Shang, Yao, Ling, and Chien-Po scale the palace wall and quickly overcome the Hun guards. Just as Shan Yu moves to strike the Emperor down, Shang attacks him and Chien-Po carries the Emperor to safety. Just as the Emperor escapes, Shan Yu overpowers Shang and soon recognizes Mulan as the soldier who caused the avalanche. Mulan lures him to the palace rooftop, where he attempts to kill her, until Mushu aims a firecracker at Shan Yu, which propels him into a tower full of fireworks and presumably to his death.
Role in the series
Shan Yu reprises his role from the movie, only to be now aided by Jafar and the Heartless from the Land of Dragons. acorreding to Chi fu, the huns and the villain leage are supposed to be enemies, but it seems Dark Cynder and Jafar managed to convince Shan Yu that it's time for the huns and villain leage to settle their defferences. as of now, Shan yu is now a villain leager himself, along with his huns, as reinforcement characters.