Time Lord
In the revived series, there were instances in which evil alien species have stolen Time Lord technology for their own purposes but such is its complexity that they are unable to operate it, as illustrated in "Doomsday" when the Genesis Ark was stolen by the Daleks and even they could not open it. Furthermore, the Genesis Ark was just one Time Lord prison that held millions of Daleks, demonstrating "bigger on the inside than it is on the outside" Time Lord technology. The classic series also makes reference to the inability of other races to successfully use Time Lord technology, with "The Two Doctors" stating that even if a race managed to copy and build their own TARDISes, they would be ripped apart by the molecular stresses of time travel as all TARDISes have a fail-deadly approach to unauthorised use unless primed with a Rassilon Imprimatur, creating a symbiotic link to a specific Time Lord.