Davros

"To hold in my hand, a capsule that contained such power. To know that life and death on such a scale was my choice. To know that the tiny pressure on my thumb, enough to break the glass, would end everything. Yes! I would do it! That power would set me up above the gods! And through the Daleks, I shall have that power!"

- Davros

Davros is a main antagonist in the Doctor Who series who created the Daleks, the single most recurring and dangerous of the Doctor's many enemies. Despite having been killed many times, he allways returns leading some to believe he is immortal, which he has claimed to be. He was played by Michael Wisher in 1975, David Gooderson in 1979, Terry Molloy from 1984 to 1988 and in 2008 by Julian Bleach.

History
Davros is a scientist from the planet Skaro whose people, the Kaleds, were engaged in a bitter thousand-year war of attrition with their enemies, the Thals. The conflict left him horribly scarred and crippled, with one functioning hand and one cybernetic eye mounted on his forehead to take the place of his real eyes and a self-designed mobile life-support chair which encloses the lower half of his body. As head of the Elite Scientific Division, Davros created to devise new military strategies in order to win the war yet realized that the overuse of nuclear and biological weapons is mutating his people. Artificially accelerating the process to examine the ultimate evolutionary end product, he created the beings that he would christen the Daleks. As a result, Davros's research was frown upon as he schemed to have the remaining Kaleds opposing him killed off. But Davros, finding his creations to be beyond his control, is shot by a Dalek and placed in suspended animation while buried in the underground of Skaro.

First encounters with the Doctor
The fourth incarnation of the Doctor, among with his companions Sarah Jane Smith and Harry Sullivan, was sent to Skaro by the Time Lord to negate the creation of the Daleks to avert a future time when Daleks would dominate the universe. However, the attempt failed as the Doctor eventually realized the consequences that would occur. Several years after being buried, Davros is sought by the Daleks to help them break a logical impasse in their war against the android Movellans. However, the Doctor destroys the Dalek groups and hands Davros over to be placed in cryogenic suspension to stand trial on Earth. Found guilty, he was placed in a space station prison for nine decades until he is freed by a small Dalek force aided by human mercenaries and Dalek duplicates.

Vowing to get revenge on the doctor, Davros learns that Daleks lost their war against the Movellans due to the development of a virus that specifically attacks Dalek tissue, and have awakened Davros to find a cure. Despite Lytton's reservations, Davros demands that he remain on the prison ship while working on the virus, as it may be necessary for him to be refrozen. However, feeling his creations to be too treacherous as he placed them and the humans under his control, Davros ultimately releasing the virus to kill off the Daleks with the intention to create a new and improved Dalek race.

Dalek Civil War and Time War
After eluding the Doctor's Fifth incarnation, Davros encounters the Sixth Doctor while he assumed the identity of the planet Necros's "The Great Healer" to create new white-colored Imperial Daleks from frozen bodies. Davros also created a clone of his head to serve as a decoy for assassins. However, the Daleks loyal to the Supreme Dalek learned of their creator's location and manage to take Davros to face judgement at Skaro for his actions against them. However, the Imperial Daleks followed with a civil war among the Daleks with Davros physically transplanted into a customised Dalek casing and calling himself Emperor of the Daleks. Fearing the Daleks' civil war, the Seventh Doctor tricks Davros into using the Time Lord artefact known as the Hand of Omega which makes Skaro's sun go supernova to wipe out Skaro and the Daleks. However, Davros entered his escape pod and escaped his destruction. Eventually, Daleks and the Time Lords engaged in a mutually destructive Time War with Davros leading his creations before what was thought to be his died during the first year of the Time War, when his command ship was devoured by the Nightmare Child at the Gates of Elysium despite the Doctor's failed efforts to save him.

Journey's End
But in reality, though the event was time-locked to prevent temporal tempering, Davros was saved by Dalek Caan of the Cult of Skaro. Guided by the maddened Caan's gained prophetic visions, Davros created new Dalek race using most of his flesh. Though Davros talks about his "new empire", he is kept prisoner in the Crucible's Vault and used by the Daleks for his scientific knowledge as he instructs them to steal 27 planets, including Earth, and hide them in the Medusa Cascade, one second out of sync with the rest of the universe. Davros planned to detonate a "reality bomb", a wavelength transmitted by the stolen planets which cancels out the electrical field binding atoms, reducing the whole of creation to nothingness with only Crucible and its contains unaffected.

Though the Tenth Doctor attempted to stop him, Davros breaks him by pointing out that he turned his companions into killers and caused countless deaths in the process. By that time, however, Davros finds himself betrayed by Caan, who realized the evilness of his race from seeing the entirety of time and his prophecies and influence to cause the Daleks' destruction with the Doctor's companion Donna Noble being infused with Time Lord DNA and the human Doctor clone created in the process. Though the Doctor attempted to save him, Davros furiously refuses the Doctor's offer to take him to safety while screaming his final words as the Crucible self-destructs: "Never forget, Doctor, you did this! I name you forever: You are the Destroyer of Worlds!"

Trivia
In continuing the Nazi themes with the Daleks, Davros could be compared to Josef Mengele in inhuman experiments for the sake of genetic perfection.