Dilating Door: Actually, most doors are regular doors, except for doors in space – because of the whole opening/closing against pressure issue – which tend to be cog-doors that roll into place. (In addition to the pressure advantage, they’re also relatively easy to open or close when the power is out, by disconnecting the actuator arm and cranking them manually, or rolling them physically.)
There are also doors which melt to let people through, except since they’re actually the power of Sufficiently Advanced Nanotech walls to reshape themselves any way they feel like, and the doors aren’t bound to appear in any particular position, well… (These are mostly the province of the absurdly wealthy who just hate messing up the nice sleek lines of their space yacht with overt door openings.)
And the people heavily into organic technology for houses and starship interiors (see that trope) and other such things generally have “doors” that are actually sphincters, or heart valves writ large. The effect is much the same.