Betrayal

Sontaran Commander Stenck acknowledged that he was committing the "ultimate betrayal" by releasing the Lupari shield which he had previously promised as a means of protection for the Daleks and the Cybermen from the final Flux event, resulting in the destruction of their space fleets. Indeed, the Dalek War Fleet, upon seeing that the Lupari ships were reforming, observed "this is a betrayal". (TV: The Vanquishers)

During the Dalek-Movellan War, the Dalek Supreme of the Kembel Faction accused Davros of betraying the Daleks by forming an alliance with the Movellans. When this was revealed to be but a ruse to lower the First Movellan's guard so Davros could upload a computer virus into the androids' network, the Supreme instead praised Davros's loyalty, the Dalek creator stating that he would never betray his creations. (AUDIO: The Triumph of Davros) In the post-Time War, New Dalek Empire, Davros accused Dalek Caan of betraying the Daleks after learning of his role in manipulating events so that Donna Noble would become the DoctorDonna and thus prevent the New Dalek Empire from detonating the reality bomb. Caan retorted that, having broke through the time lock, he had saw the Daleks, the truth of what they had done throughout time and space and decreed "no more". The Supreme One assumed that the failure of the reality bomb was a betrayal by Davros and attempted to exterminate him only to be destroyed by Jack Harkness. (TV: Journey's End)

The Twelfth Doctor considered Clara Oswald to have betrayed him when she attempted to force him to undo Danny Pink's death, though he noted he cared for her enough that betraying him made no difference in their relationship. (TV: Dark Water) In an alternate timeline however, the Twelfth Doctor initially did not forgive Clara for her betrayal, evicting from the TARDIS, though he eventually forgave her and came to regret his decision. The alternate Twelfth Doctor, knowing his timeline should not be, attempted to brainwash his past self to not forgive Clara's betrayal, only for a past version of Clara to convince him to halt his scheme. (COMIC: Four Doctors)

In the Unbound Universe, the Brigadier declined to return to England because of, among other things, being betrayed by people he'd thought were friends. (AUDIO: Sympathy for the Devil)