A vivacious young American woman traveling in Europe with her family, known for her beauty and her enjoyment of social gatherings. Her actions often challenge the expectations of European society.

An unnamed observer who tells the story from Frederick Winterbourne's perspective while providing additional insights into his character. This narrative style leaves some character details ambiguous.

Frederick Winterbourne’s wealthy and socially conservative aunt, residing in Europe. She is critical of Daisy Miller's behavior and upholds traditional social standards.

A well-off American living in Rome, known for her strict adherence to social propriety. She initially welcomes Daisy but later disapproves of her conduct in public settings.

Daisy Miller's mother, who is perceived as uninterested in social norms and often defers to Daisy's wishes. She becomes a subject of social scrutiny due to her perceived lack of concern for her daughter's reputation.