Doctor Who episode 508: Destiny of the Daleks – Episode Three (15/9/1979)
Both Philip Hinchcliffe and Graham Williams preferred to invent new baddies rather than rely on old ones, and Davros is the first monster/villain to debut during Tom Baker’s run to get a return appearance. Fittingly, it’s in one of those “Hitler resurrected” type stories beloved of pretty much all 1970s telefantasy, where it turns out he’s been frozen in the bunker for years only to rise again to wreak vengeance.