withholder

/wɪðˈhoʊldər/
noun
  1. A person or entity that deliberately keeps something back or does not give something that is expected or owed.
    • As a withholder of funds, the bank faced legal action from the charity.
    • The withholder of the secret finally confessed after years of silence.
    • The withholder of the information refused to share the key details with the team.