General:
* Foreign: This is the most common and general term.
* International: This refers to something involving more than one country.
* Overseas: This refers to something coming from or located across the sea.
More specific:
* Alien: This refers to something that is not native or natural to a particular place.
* Extraterritorial: This refers to something that is outside the jurisdiction of a particular country.
* Exogenous: This refers to something that originates from outside of a particular system or organism.
The best word to use will depend on the specific context and the nuance you are trying to convey.