Revan was born a few years after the end of the Exar Kun War. Revan became a Jedi Knight by the time of the Mandalorian Wars.
The Mandalorian Wars started when the Mandalorians, under the leadership of Mandalore the Ultimate, sought to conquer the galaxy. The Mandalorians devastated the Republic's defenses and began terrorizing systems from the Tingel Arm to the Mid Rim.
Eventually, Revan found a Jedi named Malak and they became close friends. Revan, Malak and several Jedi disagreed with the Jedi Council, who vowed that no Jedi should partake in the Mandalorian Wars.
Revan, Malak, and their followers, known as the Revanchists, fought the Mandalorian invaders alongside the Republic military, much to the latters' relief. With the rebel Jedi's aid, the Republic managed to turn the tide of the war in their favor. Revan and his forces managed to push the Mandalorians out of Republic space.
In the final battle of the war, Revan killed Mandalore the Ultimate in single combat. Soon after, he activated a super weapon which destroyed the entire planet of Malachor V. Though Revan had defeated the Mandalorians and ended the war that day, he destroyed Malachor V, and took the lives of thousands of Republic soldiers and Jedi.
Descent into Darkness
Not convinced that the Mandalorian threat was over, Revan and Malak pursued what was left of the Mandalorian armies into Deep Space. There, they discovered that the Sith Empire was not completely destroyed in the Great Hyperspace War as the Jedi Order once believed. On Dromund Kaas, they confronted a the evil Sith Emperor. They weren't strong enough to defeat the most powerful Sith Lord at that time. They're unwilling fall to the dark side was complete.
They left as heroes and returned as conquerors.
Jedi Civil War
On behalf of their new master, Darth Revan and Darth Malak's new mission as the Dark Lords of the Sith were to recover the maps leading the ancient Star Forge, an ancient warship building station build by the Rakatta centuries ago. With the Star Forge, the Sith Emperor planned to accelerate construction of the Imperial Navy, thereby being able to attack the Jedi and the Republic centuries ahead of schedule.
However, the ambitions' of the newly appointed Sith Lords grew to the point where they began to have visions of their own Empire. They formed their own Sith Empire and launched a war against the Republic that lasted for a few years.
Fortunately, as happens so often, the dark side turned upon itself. Malak's thirst for power and ascension caused him to attempt to kill Revan. He attacked his former master's starship and left him for dead while a Jedi strike team was attempting to capture him at the same time.
Wounded and unconscious, Revan was taken by a Jedi boarding team back to Republic space. His memory was erased and he was retrained as a Jedi by his future wife, Bastilla Shan. After fighting the Sith and recovering his memory, Revan slew his former apprentice, destroyed the Star Forge and ended the Jedi Civil War.
Though the Sith Emperor's plan to accelerate his return was crushed, the construction of the Sith Armada continued unchecked in deep space. The very patient Sith Emperor knew it was only a matter of time.
Revan was again celebrated as a hero and he married Bastilla Shan. Eventually though, memories of what happened to him and Malak after the Mandalorian Wars began to surface. Visions of a greater evil began to enter his memory. Putting his wife and unborn child in good hands, Revan went back into deep space in search of the unknown evil, never to be heard from again until the Sith Empire's return 300 years later.
Behind the Scenes
Revan, as a Sith Lord, along with Darth Bane was initially set to make an appearance in the Clone Wars television series episode "Ghosts of Mortis". Revan and Bane were originally supposed to be the influence behind the Son's evil deeds. The scene was created, however George Lucas chose to delete it because it conflicted with his idea of the Force. Therefore, his is not considered canon.
- Revan's exact name and identify are never confirmed, the name "Revan" is an assumed title not the name the individual was born to. Furthermore the gender and origins of this character were equally shrouded in mystery any use of the pronoun "he" is used for lack of a better term. Revan's appearance and gender were later expanded on in the new MMO, Star Wars: The Old Republic.
- Ghosts of Mortis (Deleted scene only)