Name: Mr Smith
Voiced by: Alexander Armstrong
Home Planet: Unknown
Species: Xylok (crystal)
First Appearance: Invasion of the Bane (2007)
More Information: Mr Smith is hidden behind the chimney breast in Sarah Jane's attic at 13 Bannerman Road. It reveals itself on the vocal command "Mr Smith, I need you," although it is capable of self-activation. When it reveals itself as requested a fanfare plays. It can also request the attention of Sarah Jane and be heard quite clearly from her living room, a full three floors below.

Name: K-9
Voiced by: John Leeson
Home Planet: Bi-Al Foundation, on K4067 - an asteroid near Titan
Species: Robot
First Appearance: Invasion of the Bane (2007)
More Information: Sarah Jane Smith's pet robot dog, K-9 Mark IV, is away sealing a black hole created by scientists in Switzerland. His orbit brings him into brief contact with Sarah Jane every so often, as seen in "Invasion of the Bane". He also plays a major role toward the end of The Lost Boy, by exchanging laser fire with Mr. Smith and allowing Sarah Jane to download the Armageddon Virus into Mr. Smith before returning to seal the breach.