Or, Twenty Five* Times the Tanakh Warns Us Against Mistreating the גר
There are many different possible translations for the Biblical Hebrew גר (ger) which usually refers to one of foreign birth or nationality that lives among those of a different nationality. Common translations include "sojourner, stranger, and alien and resident alien." Since the root of the word indicates temporariness of stay and any type of permanent stay is made explicit by the usage of גר תושב (ger toshav, the resident ger or resident alien) or some form of הגר הגר אתכם (ha-ger ha-gar itkhem, the ger who lives among you), the word sojourner seems most accurate of the bunch.
However, in its modern usage, the word sojourner now sounds antiquated and, perhaps more importantly, it has lost its stigma. The גר is stigmatized; that much is clear in Tanakh. The גר is as vulnerable to abuse as the widow and the fatherless. With that in mind, I have chosen to translate גר as migrant (a term familiar to those of us who know of the struggle and oppression of the migrant worker) and גר תושב and different forms of הגר הגר אתכם as immigrant - the one who has migrated to live among us.
These translations are not perfect. Most notably, the גר may actually be children or descendants of migrants or immigrants. But I have found that the need to preserve the sense of stigma the גר faces in society outweighs the option to use a different translation.
*In Bava Metzia 59b, R' Eliezer mentions 36 times Tanakh warns us against this, and other Tannaim say 46 times. So this sheet must be a work in progress!