St. Perpetua lived and died a martyr in the 1st Century (AD). Her diary, written in captivity before her martyrdom, is one of the earliest known accounts by a woman Saint.
Her account (and the follow up account of her martyrdom by witness) can be read here:
The Passion of the Holy Martyrs Perpetua and Felicitas (Felicity)
A Short life of St. Perpetua
A Short life of St. Felicity