Skaro

Skaro is the home planet of the Daleks and where they had their first encounter with the Doctor.

Details
Skaro was a planet of roughly the same mass and dimensions as Earth, and the twelfth planet from its sun. It had a single continent that was divided into east and west halves of almost equal size. When the Doctor first visited the planet, it was a nuclear wasteland, whose principle features were a petrified forest, a lake containing dangerous mutations, and the Dalek city. (The Daleks)

Skaro was the home of two races, the Kaleds (or Dals) and the Thals. Both races went to war with each other, and the resulting mutations set in motion by the weapons used were soon seen by Kaled scientists as being the end of their species in its "pure" form. The Kaled chief scientist, Davros, accelerated the mutations and placed the results in travel machines. These creatures then became the successors to the Kaleds, the dreaded Daleks. (Genesis of the Daleks)

The Thals were eventually driven from Skaro by the Daleks. The planet, however, was devastated. Its seas were dead and its surface devoid of all life. However, Skaro was rich in minerals which the Daleks used to build armies to conquer and destroy other worlds, building an interstellar empire. Some time afterward, the Daleks also abandoned Skaro. It was later reoccupied by the Imperial Dalek faction, under the orders of Davros.

Skaro was apparently destroyed sometime in the 30th Century through the actions of the Seventh Doctor, when the stellar manipulator device known as the Hand of Omega triggered a supernova in Skaro's sun (Remembrance of the Daleks).

The Master was put on trial on Skaro by the Daleks and exterminated so this presumably took place in the relative past of Skaro's timeline before its destruction, as the Eighth Doctor does not comment on it.

In the Eighth Doctor Adventures novel War of the Daleks by John Peel it was revealed that Skaro had not in fact been destroyed. The Daleks, via time travel, had discovered records that showed Skaro's destruction. After an attempt to change history (in Day of the Daleks) was unsuccessful, they terraformed the planet Antalin to resemble Skaro and manipulated Davros and the Doctor into ensuring that Antalin was destroyed in the original's place. The novel's canonical status, like all spin-off media, is debatable. In fact, it was so badly received by some fans that they even disavow it within the continuity of the novels.

Doctor Who serials that take place on Skaro or feature Skaro prominently are The Daleks, The Evil of the Daleks, Genesis of the Daleks, Destiny of the Daleks and Remembrance of the Daleks. Skaro was also the setting for the Peter Cushing feature film Dr. Who and the Daleks (1965).