Shout out to the Cawood Publishing Monster books, especially Monsters of the City, Monsters of the Underworld and Monsters of Feyland. Each monster has an obvious place in games, often filling gaps that WotC and others have bafflingly left vacant (Monsters of the City is pretty much a must for urban campaigns, IMO), and they've got actual personality, rather than just being a pile of combat stats with no obvious hook or place in an ecosystem, which too many monster books are guilty of, IMO.
The Stygian Library is an adventure that, IMO, every fantasy RPG DM should pick up ASAP (and I could definitely see Doctor Who GMs wanting it as well). It's a procedurally generated infinite library demiplane that gets increasingly creepy and weird as one goes -- it starts with a Discworld tone and approaches something more like Wraith: The Oblivion at its deepest levels. It has extremely light OSR stats that can be easily adapted to any other game. I've used it for a Strixhaven one-shot (be careful about going into the deepest recesses of the Biblioplex) and am already scheming about using it in Shadowdark.
I will break the rules, like a bunch of other folks have, and mention a setting. Ptolus is legendary for a reason and has supported 17 years of campaigning for me and will easily support 17 more.