Heinrich Institoris, born Heinrich Kramer around 1430, was a German Dominican friar and inquisitor. He is primarily recognized for his significant role in the early modern witch trials, largely due to his widely circulated book, the Malleus Maleficarum, published in 1487. This work detailed witchcraft and advocated for methods to eradicate witches, profoundly influencing the era's persecutions.

Institoris's career as an inquisitor began early in his Dominican Order membership, eventually leading him to be appointed inquisitor for regions including Tyrol, Bohemia, and Moravia. His efforts to prosecute alleged witches sometimes met resistance, as seen in his disputes with Bishop Georg Golser in Innsbruck. Following these conflicts, Institoris began compiling his treatise on witchcraft, which became the Malleus Maleficarum. Despite condemnation from some theologians at the Faculty of Cologne for its procedures, the book, prefaced by Pope Innocent VIII's bull "Summis desiderantes," gained considerable influence. He continued his work as an inquisitor and preacher until his death in 1505.

Heinrich Institoris served as a Dominican friar and inquisitor, appointed to regions such as Tyrol, Bohemia, and Moravia. His activities as an inquisitor, particularly his pursuit of individuals accused of witchcraft, led to significant controversy. A notable instance involved his interactions with Bishop Georg Golser in Innsbruck, where Institoris's methods, especially concerning the interrogation of Helena Scheuberin, drew criticism and ultimately led to the suspension of trials in the area. This conflict, coupled with criticism of his investigative procedures, spurred Institoris to compile his influential treatise on witchcraft. The papal bull "Summis desiderantes," issued in 1484, which acknowledged the existence of witches and empowered inquisitors, was incorporated into his work. This book, known as the Malleus Maleficarum, was published in 1487 and became a foundational text for the witch trials of the early modern period, detailing witchcraft and advocating for its eradication.

Following the controversies in Innsbruck, Heinrich Institoris faced initial setbacks, including the Faculty of Cologne's condemnation of the Malleus Maleficarum for its perceived unethical and illegal procedures, deviating from orthodox demonological doctrines. However, his prestige grew, and he was sought for expert consultation on witch trial procedures by the Nuremberg council in 1491. He also delivered popular lectures and disputations in Venice, patronized by the Patriarch. During this period, he authored several other treatises, including works on the Eucharist and defenses against groups like the Picards and Waldenses. His inquisitorial assignment was later updated by Pope Alexander VI, extending his authority to Bohemia and Moravia. He continued his writing and preaching until his death in Moravia in 1505. Dominican chroniclers later regarded him as a significant figure within their Order.