A more precise term would be leaker, as somebody who commits a data breach or spillage (military term). Manning did release evidence that appears to constitute a potentially criminal act, however the quantity and material subject of information leaked greatly exceeded any single, or collection of, criminal acts at 750,000 unrelated items.

A whistleblower is a subset of leaking with the limited intention of exposing something specifically nefarious.

* https://en.wikipedia.org/wiki/Whistleblower

* https://en.wikipedia.org/wiki/Data_breach

* https://en.wikipedia.org/wiki/Spillage_of_classified_informa...