Are 'Dungeon Critters' actual types of models or are you just using that term as slang for DS models? ...cuz if the former, I have no idea, but if the latter, then yes they should have bases. A few of my models came 'detached' from their bases but the base piece was still in the bag. Hope that helps.
Dungeon critters(dwellers) were an add on in the kickstarter that came with some large resin rats and spiders. One of the upgrades that mantic did a horrible job in fufillment for.