Deneb was a star orbited by multiple planets.
According to one account, Dr Who was driven to travel back to the 2150 Dalek invasion of Earth because he had seen records on the Earth of the year 3000 of an alien invasion at that time. These records described the invaders are originating from the planet "M-1", which orbited Deneb. (COMIC: Daleks, invasión a la Tierra año 2150 [+]Alfredo Grassi, adapted from Daleks' Invasion Earth 2150 A.D. (David Whitaker and Milton Subotsky), Editorial Columba (1978).) In other accounts, the Daleks' homeworld was identified as Skaro, (TV: Dr. Who and the Daleks [+]Milton Subotsky, adapted from The Daleks (Terry Nation), Dalek films (1965).) parts of a "Skaro system" with twelve or more planets orbiting it. (PROSE: Dalek Combat Training Manual [+]Richard Atkinson and Mike Tucker, BBC Books (2021).)
Other planets documented as orbiting Deneb in other accounts included Deneb-3, (COMIC: Under the Volcano [+]Si Spencer, DWA comic stories (BBC Magazines, 2006).) Deneb IV, (AUDIO: The Ultimate Adventure [+]Terrance Dicks, adapted from The Ultimate Adventure (Terrance Dicks), The Stageplays (Big Finish Productions, 2008).) and Deneb-7. (PROSE: The Touchdown on Deneb-7 [+]Paul Neary, DWM comic stories (Marvel Comics, 1981).)
Behind the scenes
As Daleks' Invasion Earth 2150 A.D. [+]Milton Subotsky and David Whitaker, adapted from The Dalek Invasion of Earth (Terry Nation), Dalek films (1966). was released in Argentina long before Dr. Who and the Daleks [+]Milton Subotsky, adapted from The Daleks (Terry Nation), Dalek films (1965). (or any other version of the original The Daleks [+]Terry Nation, Doctor Who season 1 (BBC tv, 1963-1964). narrative), the comic adaption Daleks, invasión a la Tierra año 2150 [+]Alfredo Grassi, adapted from Daleks' Invasion Earth 2150 A.D. (David Whitaker and Milton Subotsky), Editorial Columba (1978). was written for an audience unfamiliar with the otherwise-established Dalek homeworld of Skaro. Deneb is a real star in the Milky Way, though it is not known to be orbited by any planets, let alone inhabited ones. It is unclear whether one should understand "M-1" to be human astronomers' name for Skaro (identifying one of Skaro's "two suns" as Deneb), or a differing, perhaps diegetically mistaken account of the Daleks' origin.