Tara Mishra was a companion of the Ninth Doctor.
When Albion Defense, a competing anti-alien organisation, attempted to stage a series of attacks with telepathically-created monsters to create the impression that UNIT were incompetent so that they could take over Earth's anti-alien defence for themselves, Tara sacrificed her career to protect UNIT by appearing on a talk show and claiming that she was a member of Albion Defence to expose their crimes.
According to Tara's story the "monsters" were the result of hallucinogenic drugs introduced into the water supply with the resultant damage being explained as the result of a series of controlled explosions. As proof, she produced covert footage of Albion's director Jasper Corrigan ordering the attacks, carefully edited to conceal the real method.
The Doctor concocted a plan to have himself arrested for Tara's murder. Tara herself was alive and well. Her part of the plan was to free the Doctor from his imprisonment in the Hesguard Institute. (COMIC: Sin-Eaters)
The Doctor sent Jack to pick Tara up and meet back with him and Rose in 1886, but the two ended up on Sultath when energy from a white hole interfered with Jack's vortex manipulator. Despite intervention from the Doctor's future daughter, the two were sucked into the white hole, ending up in the Void alongside the Doctor's other incarnations. After the Type 1 TARDIS causing the Void to devour the universe was settled, Tara and Jack found themselves on a planet that looked like Skaro. (COMIC: The Lost Dimension)