For more than two centuries, Butler's has been one of the best known, most widely consulted hagiographies. In its brief and authoritative entries, readers can find a wealth of knowledge on the lives and deeds of the saints, as well as their ecclesiastical and historical importance since canonization. Republication of the New York, 1955 edition.
Here's a sample of other books in this Dover category
The Confessions of St. Augustine by St. Augustine Influential work recalls author's mid-4th-century origins in rural Algeria; lavish lifestyle in Milan; his struggle with sexual desires; eventual renunciation of secular ambitions and marriage; and recovery of his Catholic faith.
Introduction to the Devout Life by St. Francis de Sales, Allan Ross, Allan Ross How to live a holy life in the secular world is the focus of this Christian masterpiece. It offers clear, direct advice about praying, resisting temptation, and maintaining devotion to God.