Book excerpt: This book is a complete overview of the three most dangerous and infamous spells in Harry Potter lore, commonly called the Unforgivable Curses. The spells are categorized by severity, from least severe to most severe, i.e., starting with the Imperius Curse, followed by the Cruciatus Curse, and ending with the Killing Curse. The nature of the Unforgivable Curses is described, as in why they are unforgivable in the first place. Each spell is then described: a brief history of each spell from suspected origins to present day uses, how each spell works, notable people who performed these spells and on whom, and possible ways of defending oneself against these spells. The aim of this book is to dispel or reinforce rumors regarding the Unforgivable Curses, as well as to provide a well-rounded understanding of the most notable curses typically not taught nor talked about in great length in the wizarding community. A further aim is to address how these notorious spells stand out as truly unique among the numerous spells that currently exist in Harry Potter lore and why they should be studied to further detail.