Miniaturisation

Miniaturisation was a techonology used to shrink inorganic or organic matter.

It could be performed on humanoids, under the rays of a dimensional stabiliser from a TARDIS, without causing harm. (TV: The Invisible Enemy, The Armageddon Factor)

In 1944, in England, the First Doctor and his companions Ian and Barbara experienced a miniaturisation, solved by the TARDIS. (TV: Planet of Giants)

In 1966, the faceless Chameleons miniaturised and stored young Earthlings from all over Europe; their purpose was to steal their identities, lost after a catastrophe on their planet. Planes were used as miniaturisation chambers. (TV: The Faceless Ones)

During the 57th Segment of Time, on the Ark, most of the Earth population, fleeing from their home, had been miniaturised and placed in suspended animation in order to face a 700 years journey towards Refusis II. A Minifier was the instrument geared for this purpose. Miniaturisation was administered as a sanction too. (TV: The Ark)

Similar technologies
The Master employed the technique of matter condensation with fatal outcomes, such as against a cameraman on Gallifrey. (TV: The Deadly Assassin)