monopolizer

/məˈnɑpəˌlaɪzər/
noun
  1. A person or company that gains complete control over a product, service, or market, preventing competition.
    • Regulators fined the monopolizer for unfair business practices.
    • The large retailer became the monopolizer of the local grocery market, forcing small shops to close.
    • A monopolizer can set prices without worrying about competitors.
  2. A person who dominates or takes exclusive possession of something, such as a conversation or resource.
    • The monopolizer of the office printer made it hard for anyone else to get their work done.
    • She's a monopolizer of attention, always making everything about herself.
    • At the meeting, he was a known monopolizer of the discussion, always talking over others.