Amnesia was the (usually temporary) loss of memory.
Instances of amnesia Edit
The First Doctor and Susan Foreman suffered from partial amnesia when they arrived in 1963 London, apparently caused by challenging the Time Lord rule against interfering when they left Gallifrey. (PROSE: Time and Relative) According to another account, this memory loss occurred when the Doctor stole the TARDIS and it assaulted his mind. (PROSE: Echoes of Future Past)
The First Doctor, Ian Chesterton, Barbara Wright and Susan briefly suffered from amnesia after the TARDIS' fast return switch got stuck, which would have sent it back to the creation of a solar system and resulted in its destruction. The ship crashed itself in an attempt to warn its passengers of the dangers, and a small explosion occurred in the TARDIS as the Doctor tried to correct its faulty navigation circuits, rendering all four unconscious. (TV: The Edge of Destruction)
During the Third Doctor's exile on Earth, the Time Lords suppressed his knowledge of how the TARDIS worked as part of his punishment. (TV: The War Games) They restored this knowledge when they lifted his exile. (TV: The Three Doctors)
The Time Scaphe crew lost their memories after their ship collided with the TARDIS, but regained them after Ace told them the name of their home world, Gallifrey. The TARDIS took the Doctor's memories to keep them safe from the Process, but later returned them to save itself from destruction. (PROSE: Cat's Cradle: Time's Crucible)
The Seventh Doctor and the people who had consumed the essence of the Celestial Toymaker gave themselves electroshock therapy to suppress their memories of him in an attempt to destroy him. (PROSE: The Magic Mousetrap)
The Eighth Doctor suffered from amnesia after falling into the Master's trap, requiring him to be guided by Rassilon to regain his memories by visiting and mentally linking with his previous seven selves. (PROSE: The Eight Doctors)
The Eighth Doctor, Charley Pollard and Gideon Crane suffered from amnesia after the TARDIS crashlanded in Malebolgia, the TARDIS's damaged telepathic circuits dividing the Doctor's mind between Gideon and 'Zebediah Doe' and nearly erasing Charley's mind. (AUDIO: Minuet in Hell)
The Eighth Doctor suffered from amnesia after being forced to destroy Gallifrey (PROSE: The Ancestor Cell); this was initially attributed to trauma, but was later established as the Doctor erasing his own memory to create room for him to store the compressed Matrix in his subconscious (PROSE: The Gallifrey Chronicles).
The Panjistri supplied the Kirithons with zavát which, in addition to being their main food source, weakened their resistance to telepathic suggestion, allowing the Panjistri to suppress certain memories and even the Kirithons' awareness that they should have those memories in the first place. (PROSE: Timewyrm: Apocalypse)