Tara Mishra

 was a human. She was born in Sri Lanka. (PROSE: Christmas Special)

Before joining UNIT, Tara was a nurse.

She met the Ninth Doctor, Rose and Jack on the Blaise Castle. She later revealed herself to be a member of UNIT.

Tara later sneaked aboard the Doctor's TARDIS, and greeted them. She then joined them on their next adventure. (COMIC: Official Secrets)

After a few adventures in the TARDIS, the crew were brought off course to the site of a chat show hosted by Slist Fayflut Marteveerthon Slitheen. (PROSE: Christmas Special)