Ice Governess

The Ice Governess was the reincarnation of Francesca and Digby Latimer's late governess who died in 1891, drowning in the frozen pond. The Ice Governess was animated on Christmas Eve, one year later by telepathic "snow" that embodied Francesca's fears and nightmares about her late governess coming back to life to get her. The Great Intelligence wanted to use the Ice Governess as a template to produce an army to obliterate humanity and take over the Earth.

Once reanimated, the Governess attacked the Latimer family, parroting some of the remnants of the original governess's scathing personality, but was thwarted by the Eleventh Doctor and temporarily dissolved. She then came back and learned not to melt. Thereafter, she seemed to have an obsession with saying, "That's the way to do it!", mirroring the words of the Doctor while she was coming back. He managed to trick her into following him and Clara Oswin Oswald up the stairway leading to the TARDIS to keep her away from the Great Intelligence. The Governess managed to break into the TARDIS and take Clara with her, falling over the edge of the cloud it was on and shattering on impact (mortally injuring Clara in the process, though Strax was able to use future technology to keep her alive for a time). The Doctor took the remains and kept them in the TARDIS, where she could not reconstitute herself.

The remains of the Governess presumably remained stored in the TARDIS. (TV: The Snowmen)