Doctor Pad was a researcher at "The Yard", Starfleet's research base for alien technology, in the late 2260s. Pad was noted for his novel theories about the origins and purpose of the so-called "Planet Killer" first encountered by Commodore Matthew Decker. (TOS short story: "Devices and Desires")

Pad is a nod to Trek author Peter Allan David, whose novel Vendetta included one of these doomsday machines.