Hi here u can said what you know about Malak.

I start:
Darth Malak was a Human male born on Quelii who took the mantle of Dark Lord of the Sith during the Jedi Civil War. Before taking the name Malak, Alek Squinquargesimus, nicknamed Squint, was a famed Jedi Knight and military commander. During the Mandalorian Wars, Alek gained a reputation as a headstrong warrior who would recklessly charge into danger. He befriended the Padawan Zayne Carrick, whom he assisted in bringing down the Jedi Covenant shortly before taking the name Malak. He eventually drew closer and closer to the dark side, ultimately being seduced by Sith teachings imparted to him by his closest friend, Revan. After the final battle of the Mandalorian Wars at the Sith planet Malachor V, the two twisted the allegiance of the Revanchists and Republic forces under their command, building the foundations of what would eventually become a new Sith Empire.

In his role as Revan's chosen apprentice, Darth Malak helped his Master track down the Star Maps, devices that led to the Star Forge, an ancient superweapon built by the Rakata. A year after Revan and Malak had disappeared from known Republic space, they returned and declared war on the Republic, determined to end the "tyranny" of the Jedi Order. At one point under Darth Revan's tutelage, Malak's entire jaw was removed by a lightsaber strike from Revan himself, forcing him to wear a large metal prosthesis to cover over where his jaw had once been. After the Jedi dispatched a strike team to capture Revan and Malak, he betrayed his Master, ordering the guns of his flagship to fire on Revan's flagship. Convinced that his former Master had died, Malak usurped his mantle and ruled the Sith unchallenged, brutally conquering territory after territory. He even took an apprentice of his own, a former Jedi named Darth Bandon.

It would not be long until the new Dark Lord of the Sith was proven wrong about his former Master's death; the next year, he intercepted the Jedi Knight Bastila Shan and an amnesiac Revan, whose identity as the Dark Lord had been erased by the Jedi Council and replaced with an identity that was loyal to the Republic. After Malak revealed to his former Master that he was indeed the former Dark Lord, Malak and Revan fought each other, but Shan allowed herself to be captured by Malak so that Revan and his companions could escape. The Sith Lord corrupted Shan, whom he had once considered a threat. She eventually became his apprentice, replacing Darth Bandon, whom Revan and his companions had previously killed. Now assisted by her battle meditation, Malak considered his Sith Empire to be invincible. When the Republic fleet attacked the Star Forge above Rakata Prime, a redeemed Revan boarded the ancient space station and confronted Malak in a lightsaber duel which resulted in the Dark Lord's defeat. With that, his reign as the Dark Lord ended, and the Republic was victorious.

Important:Before turnet to the dark side with Revan, Malak been a great jedi but one day revan turned him to the dark side.Malak lose his jaw in lightsaber fight with Revan...

PICTURE MALAK'S TRUE FACE AFTER ACCIDENT AND BEFORE:


Malak's Face:http://uploadpic.org/showpic-6396/the_malak_face.jpg