Refers to a person who saves others from danger, suffering, or a difficult situation. Can be used in both literal and figurative contexts.
He was a savior to many refugees.
This new treatment may become a savior for patients.
救助者 emphasizes physical rescue from immediate danger (e.g., a lifeguard or firefighter), whereas 救済者 can also refer to someone who provides relief from broader suffering or hardship.
Compound of 救済 (kyūsai, 'relief, rescue') + 者 (sha, 'person'). The word follows a standard Sino-Japanese pattern for forming agent nouns.