Boneless
From Tardis Wiki, the free Doctor Who reference
The Boneless were two-dimensional beings from another plane. They were able to reduce three-dimensional objects to two-dimensions.
The Boneless experimented and dissected three-dimensional things, and eventually learnt how to exist as three-dimensions themselves. (TV: Flatline)
Initially hoped by the Doctor to be merely inquisitive, their motives for performing their experiments was never made clear, but were eventually discovered to be malevolent, requiring the Doctor to banish them from three-dimensional space.
