Ghosts

Supernatural or not, these spooky spectres often make for a Doctor Who story replete with Hanna-Barbera-style shenanigans
Podcast N121 Before the Flood > > > >

Doc breaks Beethoven’s fourth wall to explain how a tall chap who turns people’s souls into ham radios can plot to invade the Earth from beyond the grave
Podcast N120 Under the Lake > > >

Doc leaves Clara hanging in a haunted underwater research facility or military base or oil rig