[h4ckerle]

Don't forget Stuxnet which crossed the airgap via infecting USB Devices.

https://en.wikipedia.org/wiki/Stuxnet

[defrost]

Not forgotten at all, deliberately unmentioned as I focused on crossing the air gap by means other than:

  The only way to move data to and from them is for someone to walk across the gap with physical media.

Stuxnet was walked across via physical media (USB drives).