Rahnius

Ambassador Rahnius or Rani as he is called by his friends, was an ambassador for the Galactic Alliance. His identity (and likely his skin) was taken by a member of the Slitheen family in order to fool Sarah Jane Smith. (SJA: From Raxacoricofallapatorius With Love)

Behind the scenes
Rahnius makes note of the fact that he and Rani Chandra share the same first name, uttering the phrase "The two Ranis". This is a reference to The Two Ronnies, the famous comedy series that starred actor Ronnie Corbett.