altruism: I had to look this up for the third or fourth time.
1 : unselfish regard for or devotion to the welfare of others
2 : behavior by an animal that is not beneficial to or may be harmful to itself but that benefits others of its species
Mother Theresa comes to mind.

"Martyr"??
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Psalm 119:105 Thy word is a lamp unto my feet, and a light unto my path.