The Eleven

The Eleven was the main alias used by a Time Lord criminal in his eleventh incarnation. He had a mental illness called regenerative dissonance, which manifested as his previous incarnations' personalities arguing in his mind. Each incarnation went by a sequential number.

The One
The One once worked in the Panopticon Archive, where he found information about a prototype stellar manipulator. He had a seat on the High Council. He later left Gallifrey and became a criminal. (AUDIO: The Eleven, The Satanic Mill)

The Two
The Two boasted that his "nose was particularly good at sniffing out traitors." Within the Eleven, he exposed Volstrom's betrayal of Padrac as an agent of Ollistra. (AUDIO: Songs of Love)

The Three
The Three was noted by the Eighth Doctor was one of the personalities more willing to kill. (AUDIO: The Eleven)

The Four
The Four was described by the Eighth Doctor as "weaker than the Eleven". (AUDIO: Stop the Clock)

The Six
The Six was by far the most violent of the Eleven's personalities. He would often try to get the Eleven to butcher his way through a situation, regardless of whether the victims could be of use. (AUDIO: The Eleven)

The Eight
The Eight was an aberration compared to his other incarnations, attempting to be a "good man". Using meditation, he was able to suppress the voices of his previous incarnations. He became involved with the Time Lords' (and his) future, attempting to stop the Eighth Doctor from assembling the Doomsday Chronometer. After he was killed by the Clocksmith, the Eight retreated into the Doctor's TARDIS and regenerated. (AUDIO: The Eighth Piece / The Doomsday Chronometer)

Now a thriving persona inside the Eleven's consciousness, he successfully took control of his physical body and told the Doctor about Padrac's plans to use the Resonance Engine as a means to amplify Caleera's powers. (AUDIO: Stop the Clock)

The Nine
After regenerating, the Nine initially claimed to be a new incarnation of the Doctor to Helen Sinclair and Liv Chenka. Rather than trying to be a "good man" like his predecessor, the Nine was motivated by kleptomaniac greed. Helen and Liv helped him to rob the archive on Gallifrey, but he abandoned Liv when she became suspicious. He took Helen hostage, and brought her to the Crucible of Souls. He attempted to use the Crucible to gain immortality and exorcise his previous incarnations. After being thwarted by the Eighth Doctor, the Nine stole the Clocksmith's TARDIS and ran away. (AUDIO: The Crucible of Souls)

The Ten
The Ten was known for his skills in hypnotism. He once killed a squad of Gallifreyan soldiers on Dalgar by hypnotising the first officer to kill the commander, then the second officer to the first officer, and so on. The Ten let Tessno survive the incident so that she could tell Gallifrey about what he had done. (AUDIO: Stop the Clock)

The Eleven
The Eleven was originally captured by the Seventh Doctor and imprisoned on Gallifrey. Later he managed to escape and steal a TARDIS. The Eighth Doctor was brought in to find him. The Eleven installed himself as Lord President by an ancient edict, as he created a state of emergency while the President was off-world. He used the Sash of Rassilon to freeze the Time Lords. (AUDIO: The Eleven)

The Eleven hired Fortuna and Cleaver to bring the Doctor to him. (AUDIO: The Galileo Trap)

The Eleven found the prototype stellar manipulator and planned to use the death of a Time Lord to activate it and destroy the solar system. He captured the Doctor for these means. The Eleven's plans were prevented by an unknown force, and the Doctor's screwdriver signalled for his TARDIS to land nearby, allowing him to escape. (AUDIO: The Satanic Mill)

The Eleven was once interviewed by Caleera for the archives, as he knew she was special. He convinced her to amplify her powers for his plans. (AUDIO: Scenes From Her Life) He then came to Syra as part of his plans with Caleera. He planned a trap in the mines to kill the Doctor. He also tried to kill Liv in the mines, but River Song stopped him. He wanted to use Caleera to destroy planets. (AUDIO: The Sonomancer) He sabotaged Livia's TARDIS before he went to the Crucible of Souls and found out that Veklin had abandoned it. (AUDIO: Songs of Love)

The Eleven later followed the Eighth Doctor and his companions to 1970s New York to track Ollistra and destroy the remaining Time Lords who were against Padrac's plans. There, he met The Monk and found out about the alliance of Ollistra and the Weeping Angels. He later manipulated The Monk and the Weeping Angels to do his bidding and used the latter to take the Time Lords who were hiding in New York as hostages. After a heating argument, he pushed Ollistra from the top of the building and fought the Doctor. Then, it was revealed that Padrac was just using The Eleven as a pawn, causing a commotion between his past incarnations. This pushed the Eleven to use his Time Ring to go back to Gallifrey and see the truth. The Doctor used this as his chance to follow him to Gallifrey. (AUDIO: The Side of the Angels)

The Eleven later found out that he could not enter the Capitol, and was found by Tessno outside the city. The latter almost killed him due to personal grudge, but the Doctor stopped her from doing so. The Eleven was later brought in to the headquarters of the Opposition. Tessno was asked to lock him inside a room, where he provoked Tessno by using her grudge against her. Tessno released the Eleven to challenge him, but he killed her instead and escaped. He later brought Helen as hostage and rode a Battle TARDIS to counter the plan of the Doctor to disguise as the Eleven to infiltrate Padrac's headquarters. When Caleera gave Helen the power of the Sonomancer, he was held down by Helen as the latter used the Battle TARDIS to destroy the Resonance Engine. (AUDIO: Stop the Clock)