When I did a post about using Fiend Folio as a source for aliens and monsters in a science fiction game, the idea met with a lot of enthusiasm, largely because everybody likes the Fiend Folio. I'm going to court a little more controversy today and assert that Monster Manual II may be even better in this regard.
First off the easy stuff. It's got a whole slew of dinosaurs and giant (and minimal) animals and insects. Those are mostly kind of boring though. A bit more interesting are exotic things like the aurumvorax or is it a Barsoomian honey badger? Who knows.
The cool stuff comes with the monsters that are already sort of sci-fi. The aboleth remind me a bit of Larry Niven's thrint (except in appearance) with no modification. The Vagabond's description already tells us it's from another planet. The cloaker and the crysmal likewise work pretty much as is. Memory moss is positively Star Trekian, if we only make it's power psionic instead of magical. The wemic are a lot like Poul Anderson's Ishtarians in appearance.
|Art by Wayne Barlowe|
Then there are ones that will take a little more thought. Maybe a demilich is some sort of nanoswarm? Is a Tarrasque a fearsome bioweapon of an extinct civilization? And the Modrons? Well, I figure they're probably sentient programs living in an ancient computer network, Tron or Reboot style, waiting on adventurous netrunners to stumble into their mainframe.