Name: The Trickster
Played by: Paul Marc Davis
Home Planet: Unknown
Species: Unknown
More Information: Existing outside ordinary space and time, the Trickster travelled back through time and found Sarah Jane in her teenage years, when an accident involving her best friend occurred. The Trickster swapped Sarah Jane and her friend Andrea around - Sarah Jane now drowned, Andrea lived and thus no one was present to stop the destruction of Earth. No one except Sarah Jane's friend Maria, who realised the truth...

Name: Graske
Played by: Jimmy Vee
Voiced by: Philip Hurd-Wood
Home Planet: Griffoth
Species: Graske
More Information:
The Graske are a species of alien who usually travel through time and space replacing innocent inhabitants with near-identical doubles who obey the Graske's commands. Enslaved by the Trickster, the Graske removed Sarah Jane from time leaving her in Limbo.

Name: Andrea Yates
Played by: Jane Asher, young Andrea played by Francesca Miller.
Home Planet: Earth
Species: Human
More Information: A friend of Sarah Jane's from her schooldays. In the original, 'correct' timeline, she is killed in July 1964 when Sarah was thirteen, breaking into a closed seaside pier and falling off the pier to her death. Alien intervention swaps Andrea for Sarah, creating a new timeline where Andrea is alive in the present and Sarah long since dead, leaving the Earth vulnerable to a meteor strike. Maria Jackson, still capable of remembering Sarah after the Trickster has placed Sarah Jane in limbo, confronts Andrea, who has forgotten the deal she made; however, Maria's intervention causes her to remember. She ultimately decides to go back on her deal, with the result that she is killed in 1964 after all, with one difference to the original timeline; she now manages to say 'Remember me' before falling off the pier.