The final group battle, who will be the last two to move on to the final 16?
Darth Malak:
Once known as Alek, the human who became Darth Malak started out as a refugee to the Galactic Republic after his homeworld of Quelii was attacked by Mandalorians. Trained by the Jedi Order, Alek became close friends with another human Jedi Knight named Revan and the two would soon disobey the Council by helping the Republic in the Mandalorian Wars.
After the battle of Malachor V, Revan and Malak pursued the remaining Mandalorians into the Unknown Regions and returned as allies of the Sith - declaring war on the Jedi and launching the Civil War. At some point during the conflict Malak lost his lower jaw from a lightsaber strike delivered by Revan and replaced it with the metallic prosthetic we know all too well.
During a battle with the Jedi, Malak betrayed his master, firing on Revan's vessel and left him for dead - assuming the role of the master. Darth Malak is the main antagonist of Knights of the Old Republic and is finally confronted at the end of the game.
Sir Roderick:
While not a team member, or a main character for that matter, Sir Roderick (or fully known as Sir Roderick Ponce Von Fontlebottom the Magnificent Bastard) is still one of the more interesting characters the player comes across in their travels.
Sir Roderick plays the only "Western" character who has come from the Jade Empire equivalent of England to "educate" the Far Eastern "barbarians". Many people have not taken to kindly to him and his approach to exploration but somehow he has managed to stay alive as long as he has.
In the game, the player finds him in the Scholar's Garden and can get into a debate and duel with him. If the player wins Sir Roderick is humbled and offers an additional skill for the player to learn.
Garrus Vakarian:
In Mass Effect Garrus is nothing more than a C-Sex Officer on the Citadel that Shepard encounters early on in the game. When he finds out that Shepard is investigating into the rogue Spectre Saren, Garrus willingly disobeys his superiors and leaves the Citadel with Shepard and assists in the confrontation with the Geth and Sovereign.
After the Commander is assumed to be dead in Mass Effect 2, Garrus goes underground and takes the nickname Archangel. Operating on the crime infested Omega, Garrus forms a squad of highly lethal like-minded allies who harass, assassinate, and disrupt all illegal activites on the station much to the extreme dislike of such groups as the Blood Pack, Blue Suns, and Eclipse mercenaries and also the crime-lord Aria T'Loak.
Eventually, the three mercenary bands join forces in an attempt to kill a trapped Archangel but Shepard soon comes to his aid and helps him escape. From there, Garrus rejoins the Commander as he sets out to fight the Collector's and Reapers.
Leliana:
Leliana was once a bard from the land of Orlais whose past has been recently explored in the new Dragon Age: Origins DLC "Leliana's Song". However, the player first finds her as a sister of the Chantry in Lothering after the Battle of Ostagar.
Technically, Leliana is a potential companion but I can't imagine too many people turned her offer of assistance down. She serves as a good contrast to the cynical Morrigan because of her polite and innocent personality and good nature. Lelianna is also the second female romance option for male players.