Who was known as one of the first "fire-eaters" and a supporter of John C. Calhoun?

William Yancey was known as one of the first "fire-eaters," a term used to describe radical pro-slavery advocates who were vehemently supportive of Southern rights and the expansion of slavery into new territories. Yancey's passionate rhetoric and fervent support for states' rights, paired with his alignment with John C. Calhoun's political philosophy, positioned him as a significant figure in the antebellum South.

His advocacy for a strong defense of slavery and secessionist sentiments made him a prominent voice leading up to the Civil War. In contrast, the other individuals in the list held different political views. Charles Sumner, for instance, was a staunch abolitionist and had opposing views to Yancey and Southern fire-eaters. Stephen Douglas supported popular sovereignty but took a more centrist approach to slavery than the fire-eaters. John Brown was an ardent abolitionist who directly opposed the institution of slavery and became known for his radical actions against pro-slavery forces. Overall, Yancey’s clear alignment with pro-slavery ideology and his influential role in advocating for Southern interests are what make him the correct answer to the question.