The First Protestant Martyr in Korea from Wales: The Life and Ministry of Robert Jermain Thomas explores the life and legacy of Robert Jermain Thomas, a Welsh missionary who played a pivotal role in the early Korean church. Despite facing historical misunderstandings and political distortions--especially during Japanese colonial rule and Cold War tensions--Thomas's contributions remain foundational. This book draws on previously unused primary sources to uncover his motivations, missionary strategies, and the broader historical context of his work in Wales, China, and Korea. It critically examines the myths and controversies surrounding his death during the General Sherman incident and reevaluates his status as Korea's first Protestant martyr. By tracing Thomas's journey from education to mission, the author offers a balanced and scholarly account that clarifies his true significance. This work not only sheds new light on Thomas's enduring theological and missiological impact but also invites readers to reconsider the history of Korean Christianity and its global connections. Perfect for scholars, church leaders, and readers interested in mission history, this book revives the story of a pioneering missionary whose legacy continues to influence the worldwide church.