bloviator

Example:He's just a windbag, always talking about things he knows nothing about.

Definition:A person who talks a great deal, often in a loud and boisterous manner, but who does not contribute much to the conversation.

Example:The new CEO was a blusterer, promising the world but delivering very little.

Definition:A person who brags or boasts in an exaggerated manner; someone who makes great noise or boasts, but in a way that is not backed by substance.