Fledershrew

Fledershrews were a species of bat that were near extinction on their home planet. Fledershrews gnawed at the rafters of the House of Lungbarrow. (PROSE: Lungbarrow) The Fifth Doctor described them as a common TARDIS pest. (AUDIO: And You Will Obey Me)

During his seventh and eighth incarnations, the Doctor allowed an entire colony of Fledershrews to live in his TARDIS. (AUDIO: Black and White, Nevermore, Relative Dimensions)

Shortly after the Doctor's granddaughter Susan Campbell and great-grandson Alex Campbell arrived in the TARDIS to celebrate Christmas with his eighth incarnation and Lucie Miller, the Fledershrews were all killed by the Blitzen fish. (AUDIO: Relative Dimensions)

After crashed his TARDIS in Hexford in 1984, it was left vacant for thirty two years. A colony of Fledershrews established themselves in the console room. (AUDIO: And You Will Obey Me)

During the Last Great Time War, the Eighth Doctor ejected the Fledershrews - ones that had apparently either survived the Blitzen fish or moved in after its attack - in his TARDIS while ejecting the Vashta Nerada that were also on board. He intended to pick them up again afterwards. (AUDIO: Day of the Vashta Nerada)