noun (n)

• someone who expresses strong approval(noun.person)

  Synonym:
  endorser, ratifier, subscriber
  

  source: wordnet30
• a person who transfers his ownership interest in something by signing a check or negotiable security(noun.person)

  Synonym:
  endorser
  

  source: wordnet30
• The person who indorses.(noun)

  source: webster1913