Most purely organic creatures would have little more resistance to a vacuum than would a normal human.
Non-organic creatures may or may not be able to ignore it.
Generally, it would likely be a function of the creature's physical density. Additionally...creatures from worlds with higher atmospheric pressures would take damage faster.
According to GURPS Space, a human - properly prepared - can last something like a minute before the absence of an atmosphere and other concerns overwhelm the victim. Hey, when you have a $2-3000 RPG library, you might as well use it how/whenever you can!
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