Dark Knight Sparda

Sparda is a mighty demon who is known as the "Legendary Dark Knight". Two thousand years ago, he "woke up to justice" and alone defeated Mundus and his legions. When sealing the netherworld, sensing his power had grown too strong, he intentionally sealed himself and his own demonic power in as well. Later, he escaped his prison and quietly reigned the human world and continued to preserve harmony. Before his death, he resurfaced in the modern day and married Eva, who gave birth to his twin sons, Dante and Vergil.

Before Devil May Cry 3 Manga
Sparda was once one of Mundus's loyal generals. During his time in service, he was the mentor of the twin brothers Baul and Modeus, and he entrusted his teachings to Modeus. At some point he saw the tyranny and injustice of his master and rebelled, fighting to save humanity. Before his rebellion, he made a pact with his students to live true to their aspirations and to carry them out. He alone defeated the hellish host, before moving on to the Emperor of Darkness himself. Sparda defeated Mundus, sealing him into a marble vault, and what was left of Mundus's armies retreated back into the demon world. In order to close the gateway, Sparda used his own blood, along with the blood of a human priestess, in conjunction with his sword and a mystical amulet. He poured his demonic energy into his beloved sword to close the door between realms, the Temen-ni-gru, though this also robbed him of the lion's share of his abilities. As an added measure, he also imprisoned within the tower its gatekeepers, Cerberus, Agni & Rudra, Nevan, Beowulf and Leviathan, and took the names of the Seven Sins in order to imprison them and set them as seals keeping the Temen-ni-gru underground. In Devil May Cry 4 it is revealed that he sealed another path to hell in Fortuna using the Yamato. Sparda's activities over the next two thousand years are shrouded in legend, though it is understood that for a time after defeating Mundus, he ruled over the humans before eventually vanishing. Sparda later appeared in the twentieth century where he met and fell in love with a human woman named Eva, who bore him twin sons.

Devil May Cry 3
Arkham uses the Sons of Sparda to open the gate to the Netherworld, in order to obtain the Force Edge and thus obtaining the powers of Sparda himself. While he is able to use it to temporarily take on Sparda's form, he is unable to truly resonate with it and soon transforms into a hideous mass of demonic ectoplasm.

Devil May Cry
Sparda is referenced frequently throughout the game. At the start of the battle with Mundus, Dante finally awakens the true powers of Sparda's sword, and assumes Sparda's form as a new Devil Trigger. In this form, Dante can fly, shoot fireballs from his fists, and summon a spectral dragon. While fighting on the ground during the second part of the boss battle, Dante can also charge the fireballs, and the range of his sword is greatly extended.

Devil May Cry: The Animated Series
It is revealed that Sparda once had two apprentices, the twin brothers Baul & Modeus. There is also a statue of Sparda in a park in the town where Dante lives.

Devil May Cry 4
The [Order of the Sword is a group of demon hunters that worship Sparda. Nero, the main protagonist of Devil May Cry 4 is blood linked to Sparda, and referenced multiple times in Sparda's rebellious nature.

The demon Berial implies that he encountered Sparda when he came to the Human World two millennia prior, telling Nero, "You are just like he was..."

The readings of His Holiness reveal that Sparda is not just a devil: he has emotions and can love, and in this lies his strength. This actually explains why all of those who assert to gain his power fail, as not one of them did what they did because of love for humans.

Devil May Cry 2
During Dante's first meeting with Matier, the old woman reveals that Sparda once fought alongside the Vie de Marli clan. Dante mentions that Sparda once crossed into the Demon world and returned. It is also revealed that Sparda once fought against Argosax and Bolverk