The butterfly room was a room that the Eighth Doctor kept in his TARDIS which housed a sunny hill and meadow and billions of butterflies. The Doctor enjoyed sitting on the hill and watching the butterflies. It was warmer than most of the other rooms and corridors in the TARDIS.
It housed a great variety of butterflies, including moths, Lepidoptera, great green rainwings, flutterwings, (PROSE: Vampire Science) painted ladies, Crimson Star brushtails, great purple hairstreaks, greater green chatterers, Adonises, malachites, (PROSE: Seeing I) red admirals, and blue peacocks (PROSE: The Taint)
After the Doctor escaped from his three-year imprisonment in the Oliver Bainbridge Functional Stabilisation Centre, he rested in a wicker chair on top of the butterfly room's hill. When Sam found him, the Doctor was covered in butterflies. (PROSE: Seeing I)
The Doctor adjusted the gravity field of the butterfly room to accommodate for the T'hiili after he rescued fourteen of them from the destruction of Dominion. T'vorha ate some of the butterflies. (PROSE: Dominion) The T'Hiili left the butterfly room once the Doctor found a home for them in one of the yellow dimensions. (PROSE: Unnatural History)
When the TARDIS was transformed into the Edifice, all of the butterflies were nailed to its doors. The Doctor became extremely distressed when he discovered that his butterflies had died. (PROSE: The Ancestor Cell)
When the TARDIS regained its interior dimensions after over a century of recovering from its time as the Edifice, the butterfly room was among the rooms it recreated. The Doctor and Anji Kapoor came into the room after their adventure on EarthWorld and noticed thousands of chrysalides after they sat on the hillside. (PROSE: Earthworld)