noun (n)

• a person who contributes to the fulfillment of a need or furtherance of an effort or purpose(noun.person)

  Synonym:
  assistant, help, supporter
  

  source: wordnet30
• a person who helps people or institutions (especially with financial help)(noun.person)

  Synonym:
  benefactor
  

  source: wordnet30
• One who, or that which, helps, aids, assists, or relieves; as, a lay helper in a parish.(noun)

  source: webster1913