This dissertation is an historical study of Tibetan Buddhists generally referred to as "madmen" (smyon pa), whose "madness" carries a positive valuation more often than a negative one. Technically they are referred to as "mad siddhas" (grub thob smyon pa) or "mad yogis" (rnal 'byor smyon pa). This study seeks to uncover the purpose behind the eccentric behavior that got these ascetics labeled "madmen"; this understanding is arrived at through a systematic consideration of the ascetics' eccentric behavior in the context of their actual lives, and the greater context of the historical moment in which they lived. This study views this eccentric behavior as strategic, purposeful activity, rather than being the byproduct of a state of enlightenment. This study also considers how these holy madmen have been understood by Tibetans and Euro-Americans, with the purpose of highlighting certain lines of thinking that have become commonplace within those respective discourses. This study takes into consideration "madmen" living from the 12th century to the present, but with a special focus on the three most famous exemplars of the tradition: Sangyé Gyeltsen (better known as the Madman of Tsang, 1452-1507), Drukpa Künlé (better known as the Madman of the Drukpa, 1455-1529?) and Künga Zangpo (better known as the Madman of Ü, 1458-1532). I argue that the distinctive eccentric behavior of the Madmen of Ü and Tsang is best understood as a form of "tantric fundamentalism" in that it was based on following a literal reading of the Highest Yoga tantras, enacted as a strategic response to changes taking place in late 15th-century Tibetan religious culture. The "madness" of Drukpa Künlé resulted from his taking a critical stance towards Tibetan religious culture in general. This study concludes that the "holy madman" tradition is constituted by highly self-aware individuals making strategic use of the theme of madness in the construction of their public personas. Note: Abstract extracted from PDF text