Petrus Canisius (May 8, 1521 – December 21, 1597) was a Roman Catholic teacher and preacher in Germany, Austria, and Bohemia, fighting against the spread of Protestantism.

Born in Nijmegen, then part of Germany (part of modern-day Netherlands), he became the first German to join the Jesuit order. Through his work in the order he became one of the most influential Catholic teachers of his time, especially through his "German catechism", a book that defined the basic principles of Catholicism in the German language and found many readers in German-speaking countries. By the time of his death, the Jesuit order in Germany had gone from essentially nonexistent (he was the first German member) to a powerful tool for the defence of Catholicism. He was offered the post of bishop of Vienna, but declined in order to continue his travelling and teachings. However, he was administrator of the Diocese of Vienna from 1554 to 1555.

In Nijmegen schools, a hospital and a street are named after him. In Vienna, a street (Canisiusgasse) is named after him.

Works

• (1555) Summa doctrinae christianae
• (1556) Catechismus minimus
• (1558) Parvus catechismus catholicorum