A compassionate person who unselfishly helps others, as in In this neighborhood you can't count on a good Samaritan if you get in trouble. This expression alludes to Jesus's parable about a Samaritan who rescues and cares for a stranger who had been robbed and badly hurt and had been ignored by a priest and a Levite (Luke 10:30-35). The Samaritans were considered a heretical group by other Jews, so by using a Samaritan for the parable, Jesus chose a person whom his listeners would find least likely to be worthy of concern. [c. 1600]
Figuratively, “Good Samaritans” are persons who go out of their way to perform acts of kindness to others, especially strangers.