Mira (The Fires of Pompeii)

A Soothsayer was a member of the Sibylline Sisterhood that were in Pompeii in 79 CE. She had eyes painted on the back of her hands - a sign of a soothsayer. She was the first of the Sisterhood to see the TARDIS, or "Blue Box", that had appeared in a prophecy. She had psychic powers due to breathing in dust from Vesuvius that was converting her into a Pyrovile, and could see time thanks to the rift activity there. It is likely that she died during the eruption of Mount Vesuvius. (DW: The Fires of Pompeii)

Behind the scenes

 * Actress Karen Gillan was later cast as Amy Pond, first companion of the Eleventh Doctor, played by Matt Smith, beginning in Series 5. This is the most recent example of an actor being cast in an ongoing role in Doctor Who after making a one-off guest appearance as another character, similar to Freema Agyeman's one-off character Adeola Oshodi before her appearance as the Doctor's companion Martha Jones, Eve Myles as the character Gwyneth, and Naoko Mori, credited as 'Doctor Sato', both on Doctor Who, before their roles on Torchwood, as Gwen Cooper and Toshiko Sato, respectively.
 * Coincidentally, Gillan played a Roman soothsayer in her first appearance, and a character that has a penchant for Romans as Amy Pond.