Self-sacrifice

Self-sacrifice was the giving up of one's own life to benefit others. In this way it differed from suicide.

Daleks believed that self-sacrifice was impossible because it was not logical. (TV: Destiny of the Daleks)

In the early days of Skaro, the humanoid Dalek Lodian sacrificed himself by by blowing up his ship in order to kill Zet before he could tell the new Daleks the location of Earth. (COMIC: Legacy of Yesteryear)

In 1870, Kahler-Jex sacrificed himself in order to prevent Kahler-Tek from killing any more people or races who would get caught in the crossfire of Tek's hunt for Jex if Jex were to escape to another world. (TV: A Town Called Mercy)

A Donna Noble from a parallel world sacrificed herself by walking in front of a lorry to create a traffic jam that would force her past self to reconsider the decision that would led to the death of the Tenth Doctor in the parallel world. (TV: Turn Left)

In 2050, K9 Mark I, after ensuring that Alistair Gryffen, Jorjie Turner and Starkey left the area, initiated self-destruct to stop four Jixen warriors within Gryffen Manor. Soon after, his regeneration unit regenerated him into the form of K9 Mark 2. (TV: Regeneration) As Starkey would later recall, "he gave his life... his previous life to save us." (TV: The Bounty Hunter)

In 2059, Adelaide Brooke sacrificed herself to restore the timeline after the Tenth Doctor altered it to save the crew of Bowie Base One. (TV: The Waters of Mars)

On Midnight, a Crusader 50 hostess sacrificed herself to save her passengers from the Midnight entity by throwing herself and the entity's host out the shuttle bus doors onto the surface of Midnight, exposing them both to the extreme X-tonic radiation outside. (TV: Midnight)

In the 42nd century, Kath McDonnell sacrificed herself by jumping out of the airlock of the SS Pentallian, dragging her possessed husband with her, in order to save the ship's crew from the revenge-seeking, sentient Torajii star. (TV: 42)

In 200,100, after Rose Tyler absorbed vortex energy from the heart of the TARDIS, the Ninth Doctor in turn absorbed the energy from her via a kiss in order to save her life. As a result, he regenerated into the Tenth Doctor. (TV: The Parting of the Ways)