Discworld
From Tardis Wiki, the free Doctor Who reference
Discworld[source needed] was a land in Terry Pratchett's novels.[source needed]
Izzy Sinclair asked the Eighth Doctor if they could visit Discworld. The Doctor replied that he'd been there, and it was "flat". (COMIC: Fire and Brimstone (part 1) [+]Loading...{"page":"15","part":"1","1":"Fire and Brimstone (comic story)"})