Here are some alternatives to "legal alien":
* Lawful permanent resident
* Green card holder
* Non-citizen
* Immigrant
* Person with legal residency
For example, instead of saying "He is a legal alien," you could say:
* "He is a lawful permanent resident of the United States."
* "He has a green card."
* "He is a non-citizen who lives in the United States legally."
* "He is an immigrant."
Using respectful language helps create a more inclusive and welcoming environment.