The Doctor introduces Ralph as Peri's great, great (etcetera) grandfather and tells her he can see the resemblance, especially when she frowns.
Terry Nation comes in the USS Tax Exile to patent all the rights to the Daleks before he'll allow them to make their first appearance.
Peri believes the creator of the Daleks to be Davros.
The Doctor and Peri observe that once the Daleks had their plan to steal the Earth's magneticcore in order many other races such as the Cybermen and Sontarans also came to Earth to steal it.
According to the Doctor, the science fictionwriters' handbook defines the stealing of the Earth's magnetic core as "the great cop out".
The Doctor notes that the aliens were eventually defeated thanks to the formation of the Neolithic Union of Mineworkers.
Because of the ubiquity of this race, no attempt will be made here to list every appearance in every medium. Instead, we focus on comic appearances here, and invite you to explore a complete list of appearances elsewhere.