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 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)